docs: promote Nixpkgs as an official installation method (#2775)

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

docs/getting-started/third-parties/aur.mdx

@@ -1,7 +1,7 @@
 ---
 title: AUR (Advanced)
 description: Install Seerr using the Arch User Repository
-sidebar_position: 2
+sidebar_position: 1
 ---
 
 # AUR

docs/getting-started/third-parties/nixpkg.mdx

@@ -1,30 +0,0 @@
----
-title: Nix Package Manager (Advanced)
-description: Install Seerr using Nixpkgs
-sidebar_position: 1
----
-
-import { SeerrVersion, NixpkgVersion } from '@site/src/components/SeerrVersion';
-import Admonition from '@theme/Admonition';
-import Tabs from '@theme/Tabs';
-import TabItem from '@theme/TabItem';
-
-# Nix Package Manager
-:::danger
-This method has not yet been updated for Seerr and is currently a work in progress.
-You can follow the ongoing work on these pull requests:
-  - https://github.com/NixOS/nixpkgs/pull/450096
-  - https://github.com/NixOS/nixpkgs/pull/450093
-:::
-
-<!--
-:::warning
-Third-party installation methods are maintained by the community. The Seerr team is not responsible for these packages.
-:::
-
-:::warning
-This method is not recommended for most users. It is intended for advanced users who are using NixOS distribution.
-:::
-
-Refer to [NixOS documentation](https://search.nixos.org/options?channel=25.05&query=seerr)
--->

docs/getting-started/third-parties/synology.mdx

@@ -1,7 +1,7 @@
 ---
 title: Synology (Advanced)
 description: Install Seerr on Synology NAS using SynoCommunity
-sidebar_position: 5
+sidebar_position: 4
 ---
 
 # Synology

docs/getting-started/third-parties/truenas.mdx

@@ -1,7 +1,7 @@
 ---
 title: TrueNAS (Advanced)
 description: Install Seerr using TrueNAS
-sidebar_position: 4
+sidebar_position: 3
 ---
 # TrueNAS
 :::warning

docs/getting-started/third-parties/unraid.mdx

@@ -1,7 +1,7 @@
 ---
 title: Unraid (Advanced)
 description: Install Seerr using Unraid
-sidebar_position: 3
+sidebar_position: 2
 ---
 
 import Tabs from '@theme/Tabs';