feat: add initial rustdocs workflow

.github/workflows/docs.yml

@@ -0,0 +1,64 @@
+name: Build and Serve Crate Docs
+
+on:
+  push:
+    branches: [main]
+    tags:
+      - v*.*.*
+  pull_request:
+    branches: [main]
+    paths:
+      - ".github/workflows/docs.yml"
+
+env:
+  CARGO_NET_GIT_FETCH_WITH_CLI: true
+
+jobs:
+  docs:
+    permissions:
+      contents: write
+      packages: read
+    concurrency:
+      group: ${{ github.workflow }}-${{ github.ref }}
+    runs-on:
+      - runs-on=${{ github.run_id }}
+      - runner=8cpu-linux-arm64
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Rust toolchain
+        uses: dtolnay/rust-toolchain@nightly
+
+      # TEMPORARY
+      - name: Give GitHub Actions access to private repositories
+        uses: webfactory/[email protected]
+        with:
+          ssh-private-key: |
+            ${{ secrets.GH_ACTIONS_DEPLOY_PRIVATE_KEY }}
+
+      - name: Cargo check
+        run: cargo check
+
+      - name: Build documentation
+        run: cargo doc --workspace
+
+      # We only want the index page to display workspace crates, so we build
+      # separately and copy over the index as a hack
+      - name: Build index page
+        run: |
+          cargo doc --workspace --no-deps --exclude "openvm-benchmarks" --target-dir target/doc-nodeps
+          cp target/doc-nodeps/doc/index.html target/doc/
+        env:
+          RUSTDOCFLAGS: --enable-index-page -Zunstable-options
+
+      - name: Install s5cmd
+        run: |
+          source ci/scripts/utils.sh
+          install_s5cmd
+
+      # TODO: store versioned copy of docs when new v*.*.* tag is pushed
+      - name: Sync static S3 bucket
+        env:
+          S3_BUCKET: ${{ vars.CRATE_DOCS_S3_BUCKET }}
+        run: |
+          cd target/doc
+          s5cmd sync . s3://${S3_BUCKET%/}/static/