organize the index of the user guide

Follow the model of https://docs.codeberg.org/

The pages or sections that are not relevant for Forgejo (such as
working with the Codeberg CI are not included)

The pages that have not yet been adapted to Forgejo are set to link to
the Codeberg documentation instead

v1.19/user/index.md

@@ -6,16 +6,33 @@ title: 'Forgejo v1.19 user guide'
 These documents are targeted to people who are using Forgejo but are not
 involved in running it on their machines.
 
-- [Your First Repository](first-repository)
-- [The Basics of Issue Tracking](issue-tracking-basics)
-- [Integrated Wiki](wiki)
-- [Email Settings](email-settings)
-- [Branch and tag protection](protection)
-- [Projects / Kanban boards](project)
-- [Labels](labels)
-- [Webhooks](webhooks)
-- Authentication
-  - [LDAP, PAM, FreeIPA](authentication)
-  - [OAuth2, Scoped Tokens, Client Types](oauth2-provider)
-- [API Usage](api-usage)
-- [API Reference](https://codeberg.org/api/swagger)
+- Getting started
+  - [Your First Repository](first-repository)
+  - [The Basics of Issue Tracking](issue-tracking-basics)
+  - [Integrated Wiki](wiki)
+  - [Email Settings](email-settings)
+- Collaborating with Others
+  - [Projects / Kanban boards](project)
+  - [Pull requests and Git flow](https://docs.codeberg.org/collaborating/pull-requests-and-git-flow/)
+  - [Invite Collaborators](https://docs.codeberg.org/collaborating/invite-collaborators/)
+  - [Create and Manage an Organization](https://docs.codeberg.org/collaborating/create-organization/)
+  - [Repository Permissions](https://docs.codeberg.org/collaborating/repo-permissions/)
+  - [Resolve Conflicts](https://docs.codeberg.org/collaborating/resolve-conflicts/)
+  - [Citable Code](https://docs.codeberg.org/collaborating/citable-code/)
+  - [Labels](labels)
+- Working with Git Repositories
+  - [Clone & Commit via Web](https://docs.codeberg.org/git/clone-commit-via-web/)
+  - [Tags and Releases](https://docs.codeberg.org/git/using-tags/)
+  - [Branch and tag protection](protection)
+- Advanced Usage
+  - [Generating an Access Token](https://docs.codeberg.org/advanced/access-token/)
+  - [Webhooks](webhooks)
+  - Authentication
+    - [LDAP, PAM, FreeIPA](authentication)
+    - [OAuth2, Scoped Tokens, Client Types](oauth2-provider)
+  - [API Usage](api-usage)
+  - [API Reference](https://codeberg.org/api/swagger)
+  - [Migrating Repositories](https://docs.codeberg.org/advanced/migrating-repos/)
+- See also
+  - [Codeberg guide on Git](https://docs.codeberg.org/git/)
+  - [Codeberg guide on Markdown](https://docs.codeberg.org/markdown/)