docs: fix broken anchors

[gauthier-th]

Description

Fix broken documentation anchors. This gave a warning when building docs:

Exhaustive list of all broken anchors found:
- Broken anchor on source page path = /getting-started/nixpkg:
   -> linking to #overriding-the-package (resolved as: /getting-started/nixpkg#overriding-the-package)
- Broken anchor on source page path = /using-jellyseerr/users/editing-users:
   -> linking to /using-jellyseerr/settings/general#discover-region-and-discover-language

To-Dos

• Successful build pnpm build
• Translation keys pnpm i18n:extract
• Database migration (if required)

Issues Fixed or Closed

• Fixes #XXXX