Update README.md (#20156)

Minor header and format changes.

README.md

@@ -4,13 +4,13 @@
 
 <img width="1006" alt="mattermost-hero" src="https://user-images.githubusercontent.com/7205829/136107976-7a894c9e-290a-490d-8501-e5fdbfc3785a.png">
 
-Useful Resources:
+Useful resources:
 
 - [Deployment Guide](https://docs.mattermost.com/guides/deployment.html) - Install, setup, and configure your own Mattermost instance.
-- [Admin and User Documentation](https://docs.mattermost.com/) - Learn how to run a Mattermost instance and take advantage of all the features.
-- [Developer Documentation](https://developers.mattermost.com/) - Contribute code to Mattermost or build an integration via APIs, Webhooks, slash commands, Apps, and plugins.
+- [Product documentation](https://docs.mattermost.com/) - Learn how to run a Mattermost instance and take advantage of all the features.
+- [Developer documentation](https://developers.mattermost.com/) - Contribute code to Mattermost or build an integration via APIs, Webhooks, slash commands, Apps, and plugins.
 
-Table of Contents
+Table of contents
 =================
 
   * [Try out Mattermost](#try-out-mattermost)
@@ -24,8 +24,8 @@ Table of Contents
 
 ## Try out Mattermost
 
-- [Join the Mattermost Contributor's server](https://community.mattermost.com/signup_user_complete/?id=codoy5s743rq5mk18i7u5ksz7e) to join community discussions about contributions, development and more
-- [Get started with Mattermost Cloud](https://customers.mattermost.com/cloud/signup) to try out Mattermost
+- [Join the Mattermost Contributors server](https://community.mattermost.com/signup_user_complete/?id=codoy5s743rq5mk18i7u5ksz7e) to join community discussions about contributions, development, and more.
+- [Get started with Mattermost Cloud](https://customers.mattermost.com/cloud/signup) to try out Mattermost.
 
 [![Deploy a Preview](https://www.herokucdn.com/deploy/button.svg)](https://heroku.com/deploy?template=https://github.com/mattermost/mattermost-heroku)
 
@@ -34,9 +34,10 @@ _Note: Heroku preview does not include email or persistent storage_
 ## Install Mattermost
 
 - [Deploy Guide](https://docs.mattermost.com/guides/deployment.html) - Deploy Mattermost in minutes via Docker, Ubuntu, or tar.
-- [Developer Machine Setup](https://developers.mattermost.com/contribute/server/developer-setup) - Follow this guide if you want to write code for Mattermost
+- [Developer machine setup](https://developers.mattermost.com/contribute/server/developer-setup) - Follow this guide if you want to write code for Mattermost.
+
+Other install guides:
 
-Other Install Guides:
 - [Deploy Mattermost on Docker](https://docs.mattermost.com/install/install-docker.html)
 - [Mattermost Omnibus](https://docs.mattermost.com/install/installing-mattermost-omnibus.html)
 - [Install Mattermost from Tar](https://docs.mattermost.com/install/install-tar.html)
@@ -47,36 +48,36 @@ Other Install Guides:
 - [RHEL 8](https://docs.mattermost.com/install/install-rhel-8.html)
 - [More server install guides](https://docs.mattermost.com/guides/deployment.html)
 
-## Native Mobile and Desktop Apps
+## Native mobile and desktop apps
 
-In addition to the web interface, you can also download Mattermost clients for [Android](https://mattermost.com/mattermost-android-app/), [iOS](https://mattermost.com/mattermost-ios-app/), [Windows PC](https://docs.mattermost.com/install/desktop-app-install.html#windows-10-windows-8-1), [Mac OSX](https://docs.mattermost.com/install/desktop-app-install.html#macos-10-9), and [Linux](https://docs.mattermost.com/install/desktop-app-install.html#linux).
+In addition to the web interface, you can also download Mattermost clients for [Android](https://mattermost.com/mattermost-android-app/), [iOS](https://mattermost.com/mattermost-ios-app/), [Windows PC](https://docs.mattermost.com/install/desktop-app-install.html#windows-10-windows-8-1), [macOS](https://docs.mattermost.com/install/desktop-app-install.html#macos-10-9), and [Linux](https://docs.mattermost.com/install/desktop-app-install.html#linux).
 
 [![Google Play](https://user-images.githubusercontent.com/33878967/33095356-39b6fbf8-ceb8-11e7-8a61-c3a18fa5e658.png)](https://mattermost.com/mattermost-android-app/)  [![App Store](https://user-images.githubusercontent.com/33878967/33095353-397e69b4-ceb8-11e7-8175-f95a97d5274f.png)](https://itunes.apple.com/us/app/mattermost/id1257222717?mt=8)  [![Windows PC](https://user-images.githubusercontent.com/33878967/33095357-39cab8d2-ceb8-11e7-89a6-67dccc571ca3.png)](https://docs.mattermost.com/install/desktop.html#windows-10-windows-8-1-windows-7)  [![Mac OSX](https://user-images.githubusercontent.com/33878967/33095355-39a36f2a-ceb8-11e7-9b33-73d4f6d5d6c1.png)](https://docs.mattermost.com/install/desktop.html#macos-10-9)  [![Linux](https://user-images.githubusercontent.com/33878967/33095354-3990e256-ceb8-11e7-965d-b00a16e578de.png)](https://docs.mattermost.com/install/desktop.html#linux)
 
-## Get Security Bulletins
+## Get security bulletins
 
-Receive notifications of critical security updates. The sophistication of online attackers is perpetually increasing. If you are deploying Mattermost it is highly recommended you subscribe to the Mattermost Security Bulletin mailing list for updates on critical security releases.
+Receive notifications of critical security updates. The sophistication of online attackers is perpetually increasing. If you're deploying Mattermost it's highly recommended you subscribe to the Mattermost Security Bulletin mailing list for updates on critical security releases.
 
 [Subscribe here](https://mattermost.com/security-updates/#sign-up)
 
-## Get Involved
+## Get involved
 
 - [Contribute to Mattermost](https://handbook.mattermost.com/contributors/contributors/ways-to-contribute)
 - [Find "Help Wanted" projects](https://github.com/mattermost/mattermost-server/issues?page=1&q=is%3Aissue+is%3Aopen+%22Help+Wanted%22&utf8=%E2%9C%93)
-- [Join Developer Discussion on a Mattermost Server for contributors](https://community.mattermost.com/signup_user_complete/?id=f1924a8db44ff3bb41c96424cdc20676)
+- [Join Developer Discussion on a Mattermost server for contributors](https://community.mattermost.com/signup_user_complete/?id=f1924a8db44ff3bb41c96424cdc20676)
 - [Get Help With Mattermost](https://docs.mattermost.com/guides/get-help.html)
 
-## Learn More
+## Learn more
 
-- [API Options - webhooks, slash commands, drivers and web service](https://api.mattermost.com/)
-- [See who's using Mattermost](https://mattermost.com/blog/category/customer-stories/)
-- [Browse over 700 Mattermost integrations](https://integrations.mattermost.com/)
+- [API options - webhooks, slash commands, drivers, and web service](https://api.mattermost.com/)
+- [See who's using Mattermost](https://mattermost.com/blog/category/customers/)
+- [Browse over 700 Mattermost integrations](https://mattermost.com/marketplace/)
 
 ## License
 
 See the [LICENSE file](LICENSE.txt) for license rights and limitations.
 
-## Get the Latest News
+## Get the latest news
 
 - **Twitter** - Follow [Mattermost](https://twitter.com/mattermost).
 - **Blog** - Get the latest updates from the [Mattermost blog](https://mattermost.com/blog/).
@@ -87,6 +88,7 @@ See the [LICENSE file](LICENSE.txt) for license rights and limitations.
 - **IRC** - Join the #matterbridge channel on [Freenode](https://freenode.net/) (thanks to [matterircd](https://github.com/42wim/matterircd)).
 
 ## Contributing
+
 Please see [CONTRIBUTING.md](./CONTRIBUTING.md).
 
 Any other questions, mail us at info@mattermost.com. We’d love to meet you!