update readme about tests/examples

Author: jethrodaniel

README.md

@@ -12,6 +12,53 @@ Also includes
 
 - [SDL_ttf](https://github.com/libsdl-org/SDL_ttf)
 
+## Usage
+
+TODO
+
+## Tests
+
+Build all of SDL's test programs:
+
+```
+zig build sdl-test
+```
+
+Build and run a specific SDL test:
+
+```
+zig build sdl-test-testaudiohotplug
+zig build sdl-test-testcamera -- --camera 'Razer Kiyo'
+```
+
+## Examples
+
+Build all of SDL's example programs:
+
+```
+zig build sdl-examples
+```
+
+Build and run a specific SDL example:
+
+```
+zig build sdl-examples-woodeneye
+zig build sdl-examples-snake
+```
+
+Build all Zig examples:
+
+```
+zig build zig-examples
+```
+
+Build and run a specific Zig example:
+
+```
+zig build zig-examples-ttf
+zig build zig-examples-minimal
+```
+
 ## License
 
 [Zlib](https://spdx.org/licenses/Zlib.html), same as [SDL](https://github.com/libsdl-org/SDL).