[docs] Add Boolean toggle guide

Hope this helps someone, it was fun to write. ❤️

Signed-off-by: JPikachu <jpikachu@eden-emu.dev>

docs/user/AddingBooleanToggles

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+# Adding Boolean Settings Toggles
+
+> [!WARNING]
+> This guide is intended for developers ONLY. If you are not a developer, this likely irrelevant to yourself.
+
+This guide will walk you through adding a new boolean toggle setting to Eden's configuration across both Qt's (PC) and Kotlin's (Android) UIs.
+
+## Step 1 - src/common/settings.
+Firstly add your desired toggle inside `setting.h`,
+Example:
+```SwitchableSetting<bool> your_setting_name{linkage, false, "your_setting_name", Category::RendererExtensions};```
+NOTE - If you wish for your toggle to be on by default then change `false` to `true` after `linkage,`.
+### Remember to add your toggle to the appropriate category, for example:
+Common Categories:
+- Category::Renderer
+- Category::RendererAdvanced
+- Category::RendererExtensions
+- Category::System
+- Category::Core
+
+## Step 2 - src/qt_common/config/shared_translation.cpp
+Now you can add the toggle to the QT (PC) UI inside `shared_translation.cpp`,
+Find where you wish for it to appear and place it there.
+Example:
+```INSERT(Settings,
+       your_setting_name,
+       tr("Your Setting Display Name"),
+       tr("Detailed description of what this setting does.\n"
+          "You can use multiple lines.\n"
+          "Explain any caveats or requirements."));```
+### Make sure to:
+- Keep display naming consistant
+- Put detailed info in the description
+- Use `\n` for line breaks in descriptions
+
+## Step 3 - src/android/app/src/main/java/org/yuzu/yuzu_emu/features/settings/model/BooleanSetting.kt
+Now add it inside `BooleanSetting.kt` where it should be in the settings.
+Example:
+```RENDERER_YOUR_SETTING_NAME("your_setting_name"),```
+Remember to make sure the naming of the prefix matches the desired category.
+
+## Step 4 - src/android/app/src/main/java/org/yuzu/yuzu_emu/features/settings/model/view/SettingsItem.kt
+Now you may add the toggle to the Kotlin (Android) UI inside `SettingsItem.kt`.
+Example:
+```put(
+    SwitchSetting(
+        BooleanSetting.RENDERER_YOUR_SETTING_NAME,
+        titleId = R.string.your_setting_name,
+        descriptionId = R.string.your_setting_name_description
+    )
+)```
+
+## Step 5 - src/android/app/src/main/java/org/yuzu/yuzu_emu/features/settings/ui/SettingsFragmentPresenter.kt
+Now add your setting to the correct location inside `SettingsFragmentPresenter.kt` within the right category.
+Example:
+```add(BooleanSetting.RENDERER_YOUR_SETTING_NAME.key)```
+Remember, placing matters! Settings appear in the order of where you add them.
+
+## Step 6 - src/android/app/src/main/res/values/strings.xml
+Now add your setting and description to `strings.xml` in the appropriate place.
+Example:
+```<string name="your_setting_name">Your Setting Display Name</string>
+<string name="your_setting_name_description">Detailed description of what this setting does. Explain any caveats, requirements, or warnings here.</string>```
+
+## Step 7 - Use Your Toggle!
+Now the UI part is done find a place in the code for the toggle,
+And use it to your heart's desire!
+Example:
+```const bool your_value = Settings::values.your_setting_name.GetValue();
+
+if (your_value) {
+    // Do something when enabled
+}```
+If you wish to do something only when the toggle is disabled,
+Use `if (!your_value) {` instead of `if (your_value) {`.
+
+
+## Best Practices
+- Naming - Use clear, descriptive names. Something for both the devs and the users.
+- Defaults - Choose safe default values (usually false for new features).
+- Documentation - Write clear descriptions explaining when and why to use the setting.
+- Categories - Put settings in the appropriate category.
+- Order - Place related settings near each other.
+- Testing - Always test on both PC and Android before committing when possible.
+
+### Thank you for reading, I hope this guide helped you making your toggle!