[docs] Obtanium, installing mods, external ES-DE config, section about CFW and settings (#3678)

Signed-off-by: lizzie <lizzie@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3678
Reviewed-by: DraVee <chimera@dravee.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

docs/user/ThirdParty.md

@@ -7,3 +7,62 @@ While most of the links mentioned in this guide are relatively "safe"; we urge u
 - [Nightly Eden builds](https://github.com/pflyly/eden-nightly)
 - [NixOS Eden Flake](https://github.com/Grantimatter/eden-flake)
 - [ES-DE Frontend Support](https://github.com/GlazedBelmont/es-de-android-custom-systems)
+
+## Mirrors
+
+The main origin repository is always at https://git.eden-emu.dev/eden-emu/eden.
+
+- https://github.com/eden-emulator/mirror
+- https://git.crueter.xyz/mirror/eden
+- https://collective.taymaerz.de/eden/eden
+
+Other mirrors obviously exist on the internet, but we can't guarantee their reliability and/or availability.
+
+If you're someone wanting to make a mirror, simply setup forgejo and automatically mirror from the origin repository. Or you could mirror a mirror to save us bandwidth... your choice!
+
+## Configuring Obtainium
+
+Very nice handy app, here's a quick rundown how to configure:
+
+1. Copy the URL: https://git.eden-emu.dev/eden-emu/eden/ (or one of your favourite mirrors)
+2. Open Obtainium and tap `Add App`.
+3. Paste the URL into the `App Source URL` field.
+4. Override Source: Look for the `Override Source` dropdown menu and select `Forgejo (Codeberg)`.
+5. Click `Add:` Obtainium should now be able to parse the releases and find the APK files.
+
+Note: Even though the site isn't Codeberg, it uses the same Forgejo/Gitea backend, and this setting tells Obtainium how to read the release data.
+
+## Configuring ES-DE
+
+### Method 1
+
+1. Download ZIP from [here](https://github.com/GlazedBelmont/es-de-android-custom-systems)
+2. Unzip the file and extract `es_systems.xml` and `es_find_rules.xml` to `\Odin2\Internal shared storage\ES-DE\custom_systems`.
+3. Press `Start -> Other Settings -> Alternative Emulators` and set it to Eden (Standalone).
+
+### Method 2
+
+1. Navigate to `\Odin2\Internal shared storage\ES-DE\custom_systems`.
+2. Add this to your `es_find_rules.xml`:
+
+```xml
+<!-- Standard aka. normal release -->
+<emulator name="EDEN">
+    <rule type="androidpackage">
+        <entry>dev.eden.eden_emulator/org.yuzu.yuzu_emu.activities.EmulationActivity</entry>
+    </rule>
+</emulator>
+
+<!-- Optimized -->
+<emulator name="EDEN">
+    <rule type="androidpackage">
+        <entry>com.miHoYo.Yuanshen/org.yuzu.yuzu_emu.activities.EmulationActivity</entry>
+    </rule>
+</emulator>
+```
+
+3. Add this line of text to your `es_systems.xml` underneath where the rest of your switch system entries are:
+
+```xml
+<command label="Eden (Standalone)">%EMULATOR_EDEN% %ACTION%=android.nfc.action.TECH_DISCOVERED %DATA%=%ROMPROVIDER%</command>
+```