Auto merge of #1924 - JohnTitor:upload-docs, r=JohnTitor

Upload documentation to gh-pages from GHA

I missed this on #1918 🥵

Author: bors

.github/workflows/docs.yml

@@ -0,0 +1,25 @@
+name: Upload documentation
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  upload_docs:
+    name: Upload documentation
+    runs-on: ubuntu-18.04
+    if: github.repository == 'rust-lang/libc'
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup Rust toolchain
+        run: TARGET=x86_64-unknown-linux-gnu sh ./ci/install-rust.sh
+      - name: Generate documentation
+        run: LIBC_CI=1 sh ci/dox.sh
+      - name: Upload documentation to GitHub Pages
+        uses: rust-lang/simpleinfra/github-actions/static-websites@master
+        with:
+          deploy_dir: target/doc
+          github_token: "${{ secrets.GITHUB_TOKEN }}"
+        if: github.ref == 'refs/heads/master'