Document all the Vue App environmental settings

[derick-montague]

Is your feature request related to a problem? Please describe.
No, it's related to creating transparency for UI developers to know about all the possible vue app env settings

Describe the solution you'd like
Add a section to the customization section of the UI documentation

Describe alternatives you've considered
Expecting the user to look through all the companies .env files and determine what is available, but isn't a good experience.

Additional context
Examples:

• VUE_APP_SUBSCRIBE_SOCKET_DISABLED="true"
• VUE_APP_SERVER_OFF_REQUIRED=true
• VUE_APP_SUBSCRIBE_SOCKET_DISABLED="true"
• VUE_APP_SWITCH_TO_BACKUP_IMAGE_DISABLED="true"
• VUE_APP_VIRTUAL_MEDIA_LIST_ENABLED="true"