add admin docs page, document removal of command

Signed-off-by: Benjamin Brahmer <info@b-brahmer.de>
Co-authored-by: anoy. <anoymouserver@users.noreply.github.com>

appinfo/info.xml

@@ -28,7 +28,7 @@ Report a [feed issue](https://github.com/nextcloud/news/discussions/new)
     <documentation>
         <user>https://nextcloud.github.io/news/</user>
         <admin>https://nextcloud.github.io/news/admin/</admin>
-        <developer>https://nextcloud.github.io/news/</developer>
+        <developer>https://nextcloud.github.io/news/developer</developer>
     </documentation>
     <category>multimedia</category>
     <website>https://github.com/nextcloud/news</website>

docs/api/api-v1.md

@@ -669,7 +669,7 @@ This is used to clean up the database. It deletes folders and feeds that are mar
 }
 ```
 
-**New in 8.1.0**: The console command for achieving the same result is:
+**New in 8.1.0, Removed in 16.0.0**: The console command for achieving the same result is:
 
     php -f nextcloud/occ news:updater:all-feeds
 

docs/developer.md

@@ -0,0 +1,22 @@
+# Developer
+Welcome to the Nextcloud News App developer documentation.
+
+News is open for contributions, if you plan to implement a new feature make sure to open a [discussion](https://github.com/nextcloud/news/discussions/new?category=Features). Describe the feature that you are planing and your first idea how to implement it.
+This ensures that you don't start working on something which collides with the targets of the maintainers.
+
+For small fixes and improvements feel free to directly create a PR, the maintainers are happy to review your code.
+
+## APIs
+News offers an API that can be used by clients to synchronize with the server.
+There are two API declarations, so far only V1 has been fully implemented.
+Work on V2 has started with low priority.
+
+- [API-V1](api/api-v1.md)
+- [API-V2](api/api-v2.md)
+
+## Coding Style Guidelines
+The PHP code should all adhere to [PSR-2](https://www.php-fig.org/psr/psr-2/).
+*Note that this is a different codestyle than Nextcloud itself uses.*
+To test the codestyle you can run `make phpcs`.
+
+For linting JavaScript, a [jshint file](https://github.com/nextcloud/news/blob/master/js/.jshintrc) is used that is run before compiling the JavaScript.

mkdocs.yml

@@ -10,6 +10,7 @@ nav:
   - install.md
   - clients.md
   - admin.md
+  - developer.md
   - faq.md
   - Features:
     - Custom CSS: features/customCSS.md