[Doxygen] Add documentation for beta channel. (#6510)

* [Doxygen] Add documentation for beta channel.

Took 36 minutes

* [Doxygen] Use default theme.

Took 13 minutes

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

doc/doxygen/extra-pages/user_documentation/index.md

@@ -1,9 +1,17 @@
 @page user_reference User Reference
-
-- @subpage search_syntax_help
-- @subpage deck_search_syntax_help
  
+# Deck Management
+
 - @subpage creating_decks
 - @subpage importing_decks
 - @subpage editing_decks
 - @subpage exporting_decks
+
+# Release Channels
+
+- @subpage beta_release
+
+# Syntax Help
+
+- @subpage search_syntax_help
+- @subpage deck_search_syntax_help

doc/doxygen/extra-pages/user_documentation/settings/beta.md

@@ -0,0 +1,54 @@
+@page beta_release Beta Release
+
+The beta version of Cockatrice features all the newest features before they make their way into the latest stable
+release.
+It allows us to test these features ahead of time and you to give feedback on them.
+We release new betas very frequently and usually release a follow-up beta with a fix within a day or two if we break
+anything. In contrast, stable releases are released much less frequently but ensured to be stable.
+
+# What to Expect from the Beta
+
+Using the beta and giving feedback on it helps us improve Cockatrice a lot.
+We do not perform any automatic data collection so your voluntary feedback is the only way for us to get a sense of what
+you enjoy, expect, or would like to change.
+
+We highly appreciate your active participation and feedback.
+
+That being said, some words of warning should be issued:
+
+The beta release may contain unfinished features, bugs, or performance issues.
+It is intended for testing and feedback and may be less stable than the default release.
+
+We recommend using the beta only if you are comfortable encountering issues and helping us improve Cockatrice.
+
+# Switching to the Beta
+
+To switch to the Beta, navigate to your settings, using the Tab "Cockatrice → Settings" or Ctrl + Shift + P (default
+shortcut).
+
+Within the settings, in the first tab 'General', the first section 'Personal Settings' contains the setting 'Release
+Channel'.
+
+\image html release_channel_beta.png
+
+Switch this to 'Beta'.
+
+Afterwards, close your settings, and use the 'Help' tab to search for a client update. You should be prompted to install
+the beta version.
+
+# Switching back to Stable
+
+Follow the same steps as above, but set Release Channel to 'Default'.
+
+# Giving Feedback
+
+If you encounter a bug or unexpected behavior while using the beta, please report it on:
+
+- GitHub: https://github.com/Cockatrice/Cockatrice/issues
+- Discord: https://discord.gg/4hNswvHeFd in #beta-testing
+
+When reporting issues, please include:
+
+- Your operating system
+- The beta version number (found in 'Help → About Cockatrice')
+- Steps to reproduce the problem, if possible