Sync SDL3 header -> wiki

SDL3/README/migration.md

@@ -362,6 +362,8 @@ now looks like this:
     SDL_Keymod mod = event.key.mod;
 ```
 
+The keycode in key events is affected by modifiers by default. e.g. pressing the A key would generate the keycode `SDLK_a`, or 'a', and pressing it while holding the shift key would generate the keycode `SDLK_A`, or 'A'. This behavior can be customized with `SDL_HINT_KEYCODE_OPTIONS`.
+
 The gamepad event structures caxis, cbutton, cdevice, ctouchpad, and csensor have been renamed gaxis, gbutton, gdevice, gtouchpad, and gsensor.
 
 The mouseX and mouseY fields of SDL_MouseWheelEvent have been renamed mouse_x and mouse_y.

SDL3/SDL_HINT_KEYCODE_OPTIONS.md

@@ -0,0 +1,54 @@
+###### (This is the documentation for SDL3, which is under heavy development and the API is changing! [SDL2](https://wiki.libsdl.org/SDL2/) is the current stable version!)
+# SDL_HINT_KEYCODE_OPTIONS
+
+A variable that controls keycode representation in keyboard events.
+
+## Header File
+
+Defined in [<SDL3/SDL_hints.h>](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_hints.h)
+
+## Syntax
+
+```c
+#define SDL_HINT_KEYCODE_OPTIONS "SDL_KEYCODE_OPTIONS"
+```
+
+## Remarks
+
+This variable is a comma separated set of options for translating keycodes
+in events:
+
+- "unmodified": The keycode is the symbol generated by pressing the key
+  without any modifiers applied. e.g. Shift+A would yield the keycode
+  [SDLK_a](SDLK_a), or 'a'.
+- "modified": The keycode is the symbol generated by pressing the key with
+  modifiers applied. e.g. Shift+A would yield the keycode [SDLK_A](SDLK_A),
+  or 'A'.
+- "french_numbers": The number row on French keyboards is inverted, so
+  pressing the 1 key would yield the keycode [SDLK_1](SDLK_1), or '1',
+  instead of [SDLK_AMPERSAND](SDLK_AMPERSAND), or '&'
+- "latin_letters": For keyboards using non-Latin letters, such as Russian
+  or Thai, the letter keys generate keycodes as though it had an en_US
+  layout. e.g. pressing the key associated with
+  [SDL_SCANCODE_A](SDL_SCANCODE_A) on a Russian keyboard would yield 'a'
+  instead of 'ф'.
+
+The default value for this hint is equivalent to "modified,french_numbers"
+
+Some platforms like Emscripten only provide modified keycodes and the
+options are not used.
+
+These options do not affect the return value of
+[SDL_GetKeyFromScancode](SDL_GetKeyFromScancode)() or
+[SDL_GetScancodeFromKey](SDL_GetScancodeFromKey)(), they just apply to the
+keycode included in key events.
+
+This hint can be set anytime.
+
+## Version
+
+This hint is available since SDL 3.0.0.
+
+----
+[CategoryAPI](CategoryAPI), [CategoryAPIMacro](CategoryAPIMacro), [CategoryHints](CategoryHints)
+