[CI] Add build CI based on dtk-template

ref: https://github.com/encounter/dtk-template/blob/main/docs/github_actions.md

Author: snailspeed3

.github.example/workflows/build.yml .github/workflows/build.yml.github.example/workflows/build.yml renamed to .github/workflows/build.yml

@@ -8,7 +8,7 @@ jobs:
   build:
     # This is a *private* build container.
     # See docs/github_actions.md for more information.
-    container: ghcr.io/my/game-build:main
+    container: ghcr.io/riidefi/mkw-build:main
 
     runs-on: ubuntu-latest
     strategy: