Enhance Talk user documentation

[Antreesy]

Add missing features in the docs

List of missing features

Talk 23:

• pinned messages
• scheduled message
• echo/noise/autogain
• chat layout
• live translations

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Enhance navigation / splitting content into chunks

Inspiration / Info / Templates to use:

• https://gitlab.com/tgdp/templates
  Samples:
• https://www.bycs.de/hilfe-und-tutorials/videokonferenzsystem/index.html
• https://support.bigbluebutton.org/hc/en-us/categories/1500000517381-BigBlueButton-HTML5
• https://jitsimeet.eu/hilfe/
• https://support.microsoft.com/de-de/teams (Overview is not good, but details afterwards are)

Additional notes (post here to not flood the discussion below in the issue):

• We should also look into "usecase splitting", basically have clear entry pages for Moderators and Participants so they can learn/see only the bits they need.
• Articles with multiple use (e.g. Ban participants can be mentioned in both Conversations and Webinars) should be moved to separate article and linked
• Promote / mention mobile and desktop clients for Talk (to improve experience)
• Show link to user manual in Talk app

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Core PR (to be rebased and merged last:

• fix(user): Split talk user documentation into pieces documentation#13051

Current plan for splitting

• Talk index page
  • Chat
    • Sending messages
      • Using Markdown
      • Inserting emoji
      • Smart Picker
      • Replying to messages and more -> interacting dupe?
      • Silent messages
      • Scheduling messages
      • Chat summary -> interacting?
      • ...
    • Interacting with messages
      • Editing messages
      • Pinning messages
      • Setting reminder on messages
      • Messages expiration -> conversations dupe?
      • Messages search in a conversation -> sending dupe?
      • Threaded messages
      • ...
    • Apps integrating with messages
      • Deck
      • ...
    • Attachments
      • Sharing files in a chat
      • Polls in chat
      • ...
  • Conversations
    • Conversations
      • Type of conversations
      • Talk Dashboard -> move?
      • Creating a conversation
      • Filter your conversations
      • Compact view of conversations list
      • Archive conversations
      • Managing a conversation
      • Ban participants -> webinar dupe?
      • Messages expiration -> messages dupe?
      • Notifications and privacy
      • ...
    • Open Conversations
      • Creating
      • View all
    • Appearance
      • Compact view of conversations list
      • Chat messages
    • Federation
      • Sending an invitation
      • Accepting an invitation
    • Files integration
      • Talk from Files
    • Calendar integration with Talk
      • Meetings and events
      • Schedule from Calendar
  • Calls
    • Call
      • Starting a call
      • Starting a screen share
      • Changing view in a call
      • Download call participants list
      • Call live transcription
    • Call recording
      • Manage a recording
      • Recording consent
    • Webinar
      • Lobby
    • Breakout rooms
      • Configure breakout rooms
      • Manage breakout rooms
  • Join a call or chat as guest
    • Joining a chat
    • Joining a call
    • Starting a screen share
    • More settings
    • Joining as an email guest