Update MFA help text documentation link (#4975)

* Update mfa help text with documentation link

* Update en.json

webapp/components/admin_console/mfa_settings.jsx

@@ -86,7 +86,7 @@ export default class MfaSettings extends AdminSettings {
                     helpText={
                         <FormattedHTMLMessage
                             id='admin.service.enforceMfaDesc'
-                            defaultMessage='When true, users on the system will be required to set up [multi-factor authentication]. Any logged in users will be redirected to the multi-factor authentication setup page until they successfully add MFA to their account.<br/><br/>It is recommended you turn on enforcement during non-peak hours, when people are less likely to be using the system. New users will be required to set up multi-factor authentication when they first sign up. After set up, users will not be able to remove multi-factor authentication unless enforcement is disabled.<br/><br/>Please note that multi-factor authentication is only available for accounts with LDAP and email login methods. Mattermost will not enforce multi-factor authentication for other login methods. If there are users on your system using other login methods, it is recommended you set up and enforce multi-factor authentication directly with the SSO or SAML provider.'
+                            defaultMessage="When true, users on the system will be required to set up <a href='https://docs.mattermost.com/deployment/auth.html' target='_blank'>multi-factor authentication</a>. Any logged in users will be redirected to the multi-factor authentication setup page until they successfully add MFA to their account.<br/><br/>It is recommended you turn on enforcement during non-peak hours, when people are less likely to be using the system. New users will be required to set up multi-factor authentication when they first sign up. After set up, users will not be able to remove multi-factor authentication unless enforcement is disabled.<br/><br/>Please note that multi-factor authentication is only available for accounts with LDAP and email login methods. Mattermost will not enforce multi-factor authentication for other login methods. If there are users on your system using other login methods, it is recommended you set up and enforce multi-factor authentication directly with the SSO or SAML provider."
                         />
                     }
                     disabled={!this.state.enableMultifactorAuthentication}

webapp/i18n/en.json

@@ -675,7 +675,7 @@
   "admin.service.developerDesc": "When true, JavaScript errors are shown in a red bar at the top of the user interface. Not recommended for use in production. ",
   "admin.service.developerTitle": "Enable Developer Mode: ",
   "admin.service.enforcMfaTitle": "Enforce Multi-factor Authentication:",
-  "admin.service.enforceMfaDesc": "When true, users on the system will be required to set up [multi-factor authentication]. Any logged in users will be redirected to the multi-factor authentication setup page until they successfully add MFA to their account.<br/><br/>It is recommended you turn on enforcement during non-peak hours, when people are less likely to be using the system. New users will be required to set up multi-factor authentication when they first sign up. After set up, users will not be able to remove multi-factor authentication unless enforcement is disabled.<br/><br/>Please note that multi-factor authentication is only available for accounts with LDAP and email login methods. Mattermost will not enforce multi-factor authentication for other login methods. If there are users on your system using other login methods, it is recommended you set up and enforce multi-factor authentication directly with the SSO or SAML provider.",
+  "admin.service.enforceMfaDesc": "When true, users on the system will be required to set up <a href='https://docs.mattermost.com/deployment/auth.html' target='_blank'>multi-factor authentication</a>. Any logged in users will be redirected to the multi-factor authentication setup page until they successfully add MFA to their account.<br/><br/>It is recommended you turn on enforcement during non-peak hours, when people are less likely to be using the system. New users will be required to set up multi-factor authentication when they first sign up. After set up, users will not be able to remove multi-factor authentication unless enforcement is disabled.<br/><br/>Please note that multi-factor authentication is only available for accounts with LDAP and email login methods. Mattermost will not enforce multi-factor authentication for other login methods. If there are users on your system using other login methods, it is recommended you set up and enforce multi-factor authentication directly with the SSO or SAML provider.",
   "admin.service.forward80To443": "Forward port 80 to 443:",
   "admin.service.forward80To443Description": "Forwards all insecure traffic from port 80 to secure port 443",
   "admin.service.googleDescription": "Set this key to enable the display of titles for embedded YouTube video previews. Without the key, YouTube previews will still be created based on hyperlinks appearing in messages or comments but they will not show the video title. View a <a href=\"https://www.youtube.com/watch?v=Im69kzhpR3I\" target='_blank'>Google Developers Tutorial</a> for instructions on how to obtain a key.",