PLT-5281 error messages contain a link to documentation about reserved words (#5530)

* PLT-5281 error messages contain a link to documentation about reserved words

* Updated comments per PM review

* Proposed fix to review comments

webapp/i18n/en.json

@@ -1220,9 +1220,9 @@
   "create_team.team_url.hint": "<li>Short and memorable is best</li><li>Use lowercase letters, numbers and dashes</li><li>Must start with a letter and can't end in a dash</li>",
   "create_team.team_url.regex": "Use only lower case letters, numbers and dashes. Must start with a letter and can't end in a dash.",
   "create_team.team_url.required": "This field is required",
-  "create_team.team_url.taken": "URL is taken or contains a reserved word",
+  "create_team.team_url.taken": "This URL <a href=\"https://docs.mattermost.com/help/getting-started/creating-teams.html#team-url\" target=\"_blank\">starts with a reserved word</a> or is unavailable. Please try another.",
   "create_team.team_url.teamUrl": "Team URL",
-  "create_team.team_url.unavailable": "This URL is unavailable. Please try another.",
+  "create_team.team_url.unavailable": "This URL is taken or unavailable. Please try another.",
   "create_team.team_url.webAddress": "Choose the web address of your new team:",
   "custom_emoji.empty": "No custom emoji found",
   "custom_emoji.header": "Custom Emoji",