sokol_gfx.h, sokol_app.h: update build instructions

sokol_app.h

@@ -30,7 +30,8 @@
         SOKOL_ASSERT(c)             - your own assert macro (default: assert(c))
         SOKOL_UNREACHABLE()         - a guard macro for unreachable code (default: assert(false))
         SOKOL_WIN32_FORCE_MAIN      - define this on Win32 to add a main() entry point
-        SOKOL_WIN32_FORCE_WINMAIN   - define this on Win32 to add a WinMain() entry point (enabled by default unless SOKOL_WIN32_FORCE_MAIN or SOKOL_NO_ENTRY is defined)
+        SOKOL_WIN32_FORCE_WINMAIN   - define this on Win32 to add a WinMain() entry point (enabled by default unless
+                                      SOKOL_WIN32_FORCE_MAIN or SOKOL_NO_ENTRY is defined)
         SOKOL_NO_ENTRY              - define this if sokol_app.h shouldn't "hijack" the main() function
         SOKOL_APP_API_DECL          - public function declaration prefix (default: extern)
         SOKOL_API_DECL              - same as SOKOL_APP_API_DECL
@@ -82,6 +83,11 @@
 
     On macOS and iOS, the implementation must be compiled as Objective-C.
 
+    On Emscripten:
+        - for WebGL2: add the linker option `-s USE_WEBGL2=1`
+        - for WebGPU: compile and link with `--use-port=emdawnwebgpu`
+          (for more exotic situations, read: https://dawn.googlesource.com/dawn/+/refs/heads/main/src/emdawnwebgpu/pkg/README.md)
+
     FEATURE OVERVIEW
     ================
     sokol_app.h provides a minimalistic cross-platform API which

sokol_gfx.h

@@ -66,6 +66,26 @@
 
     SOKOL_DEBUG - by default this is defined if _DEBUG is defined
 
+    Link with the following system libraries (note that sokol_app.h has
+    additional linker requirements):
+
+    - on macOS/iOS with Metal: Metal
+    - on macOS with GL: OpenGL
+    - on iOS with GL: OpenGLES
+    - on Linux with EGL: GL or GLESv2
+    - on Linux with GLX: GL
+    - on Android: GLESv3, log, android
+    - on Windows with the MSVC or Clang toolchains: no action needed, libs are defined in-source via pragma-comment-lib
+    - on Windows with MINGW/MSYS2 gcc: compile with '-mwin32' so that _WIN32 is defined
+        - with the D3D11 backend: -ld3d11
+
+    On macOS and iOS, the implementation must be compiled as Objective-C.
+
+    On Emscripten:
+        - for WebGL2: add the linker option `-s USE_WEBGL2=1`
+        - for WebGPU: compile and link with `--use-port=emdawnwebgpu`
+          (for more exotic situations, read: https://dawn.googlesource.com/dawn/+/refs/heads/main/src/emdawnwebgpu/pkg/README.md)
+
     sokol_gfx DOES NOT:
     ===================
     - create a window, swapchain or the 3D-API context/device, you must do this