CI: added github pages build job

.github/workflows/gh-pages.yml

@@ -0,0 +1,18 @@
+name: GitHub Pages
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    name: Deploy docs
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout master
+        uses: actions/checkout@v1
+
+      - name: Deploy docs
+        uses: mhausenblas/mkdocs-deploy-gh-pages@1.14
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

mkdocs.yml

@@ -0,0 +1,43 @@
+site_name: SDL
+site_description: Simple Direct Media Layer
+docs_dir: docs
+site_dir: build/docs
+repo_url: https://github.com/libsdl-org/SDL
+repo_name: GitHub
+
+theme:
+  name: readthedocs
+  highlightjs: true
+  hljs_languages: [c]
+
+markdown_extensions:
+  - toc:
+      toc_depth: 2
+
+nav:
+  - README.md
+  - README-android.md
+  - README-cmake.md
+  - README-directfb.md
+  - README-dynapi.md
+  - README-emscripten.md
+  - README-gesture.md
+  - README-git.md
+  - README-hg.md
+  - README-ios.md
+  - README-kmsbsd.md
+  - README-linux.md
+  - README-macosx.md
+  - README.md
+  - README-nacl.md
+  - README-os2.md
+  - README-pandora.md
+  - README-platforms.md
+  - README-porting.md
+  - README-psp.md
+  - README-raspberrypi.md
+  - README-touch.md
+  - README-visualc.md
+  - README-wince.md
+  - README-windows.md
+  - README-winrt.md