Update readme and workflow to mention sdl2

.github/workflows/run-nmage.yml

@@ -1,4 +1,4 @@
-name: Run-nMage
+name: Run-nmage
 on:
   create:
   workflow_dispatch:
@@ -11,8 +11,10 @@ jobs:
         uses: actions/setup-go@v2
         with:
           go-version: '^1.17'
-      - name: Get dylib
+      - name: Install asimp-go dylib
         run: sudo mkdir -p /usr/local/lib && sudo wget https://github.com/bloeys/assimp-go/releases/download/v0.4.2/libassimp_darwin_amd64.dylib -O /usr/local/lib/libassimp.5.dylib
+      - name: Install SDL2
+        run: brew install sdl2{,_image,_mixer,_ttf,_gfx} pkg-config
       - name: Clone nmage
         run: git clone https://github.com/bloeys/nmage
       - name: Run nmage

README.md

@@ -17,6 +17,7 @@ To run the project you need:
 * A C/C++ compiler installed and in your path
   * Windows: [MingW](https://www.mingw-w64.org/downloads/#mingw-builds) or similar
   * Mac/Linux: Should be installed by default, but if not try [GCC](https://gcc.gnu.org/) or [Clang](https://releases.llvm.org/download.html)
+* Install SDL2 by following their [requirements](https://github.com/veandco/go-sdl2#requirements).
 * Get the required [assimp-go](https://github.com/bloeys/assimp-go) DLLs/DyLibs and place them correctly by following the assimp-go [README](https://github.com/bloeys/assimp-go#using-assimp-go).
 
 Then you can start nMage with `go run .`