[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/Mods.md

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+# User Handbook - Installing Mods
+
+## General Notes
+
+**Note:** When installing a mod, always read the mod's installation instructions.
+
+This is especially important if a mod uses a framework such as **ARCropolis**, **Skyline**, or **Atmosphere plugins**. In those cases, follow the framework's instructions instead of using Eden's normal mod folder.
+
+For example, **Super Smash Bros. Ultimate** uses such a framework. See the related section below for details.
+
+---
+
+# Installing Mods for Most Games
+
+1. Right click a game in the game list.
+2. Click **"Open Mod Data Location"**.
+3. Extract the mod into that folder.
+
+Each mod should be placed inside **its own subfolder**.
+
+---
+
+# Enabling or Disabling Mods
+
+1. Right click the game in the game list.
+2. Click **Configure Game**.
+3. In the **Add-Ons** tab, enable or disable mods, updates, and DLC by ticking or unticking their boxes.
+
+---
+
+# Important Note About SD Card Paths
+
+Some mods are designed for real Nintendo Switch consoles and refer to the **SD card root**.
+
+The emulated SD card is located at:
+
+```
+%AppData%\eden\sdmc
+```
+
+Example:
+
+```
+Switch instruction:  sd:/ultimate/mods
+Eden equivalent:     sdmc/ultimate/mods
+```
+
+---
+
+# Framework-Based Mods (Super Smash Bros. Ultimate)
+
+Some games require external mod frameworks instead of the built-in mod loader.
+
+The most common example is **Super Smash Bros. Ultimate**.
+
+These mods are installed directly to the **emulated SD card**, not the normal Eden mod folder.
+
+---
+
+# Installing the ARCropolis Modding Framework
+
+**Note:** Some mod packs bundle ARCropolis with their installer (for example, Smash Ult-S).
+
+---
+
+## 1. Download ARCropolis
+
+Download the latest release:
+
+https://github.com/Raytwo/ARCropolis/releases/
+
+---
+
+## 2. Install ARCropolis
+
+Extract the **`atmosphere`** folder into:
+
+```
+%AppData%\eden\sdmc
+```
+
+This is the **emulated SD card directory**.
+
+Verify installation by checking that the following file exists:
+
+```
+sdmc\atmosphere\contents\01006A800016E000\romfs\skyline\plugins\libarcropolis.nro
+```
+
+---
+
+## 3. Download Skyline
+
+Download the latest Skyline release:
+
+https://github.com/skyline-dev/skyline/releases
+
+Skyline used to be bundled with ARCropolis but is now distributed separately to avoid compatibility issues caused by outdated bundled versions.
+
+---
+
+## 4. Install Skyline
+
+Extract the **`exefs`** folder into:
+
+```
+sdmc\atmosphere\contents\01006A800016E000
+```
+
+The `exefs` folder should be **next to the `romfs` folder**.
+
+Verify installation by checking that the following file exists:
+
+```
+%AppData%\eden\sdmc\atmosphere\contents\01006A800016E000\exefs\subsdk9
+```
+
+---
+
+## 5. Launch the Game Once
+
+Start the game and make sure you see the **ARCropolis version text on the title screen**.
+
+This will also create the folders required for installing mods.
+
+---
+
+## 6. Install Smash Ultimate Mods
+
+Install mods inside:
+
+```
+sdmc\ultimate\mods
+```
+
+Each mod must be placed inside **its own subfolder**.
+
+Example:
+
+```
+sdmc\ultimate\mods\ExampleMod
+```
+
+---
+
+# Troubleshooting
+
+## ARCropolis text does not appear on startup
+
+Check the following:
+
+- `libarcropolis.nro` exists in:
+
+```
+sdmc\atmosphere\contents\01006A800016E000\romfs\skyline\plugins
+```
+
+- `subsdk9` exists in:
+
+```
+sdmc\atmosphere\contents\01006A800016E000\exefs
+```
+
+- Files were extracted to:
+
+```
+%AppData%\eden\sdmc
+```
+
+---
+
+## Mods are not loading
+
+Make sure mods are installed inside:
+
+```
+sdmc\ultimate\mods
+```
+
+Each mod must have its **own subfolder**.
+
+Correct example:
+
+```
+sdmc\ultimate\mods\ExampleMod
+```
+
+Incorrect example:
+
+```
+sdmc\ultimate\mods\ExampleMod\ExampleMod
+```
+
+---
+
+## Installing mods in the wrong folder
+
+ARCropolis mods **do not go in Eden's normal mod folder**.
+
+Do **not** install Smash mods here:
+
+```
+user\load\01006A800016E000
+```
+
+That folder is only used for traditional **RomFS mods**, not ARCropolis.