workflow: Add a docs workflow

This workflow will build the docs for the zephyr crates for a single
particular build, and publish them to GH pages.

Signed-off-by: David Brown <[email protected]>

.github/workflows/docs.yml

@@ -0,0 +1,71 @@
+name: Generate and Preview Rust Docs
+
+on:
+  pull_request:
+    branches:
+      - main  # Only generate docs for PRs targeting main
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  generate-docs:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          path: zephyr-rust-lang
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: 3.11
+
+      - name: Setup Zephyr project
+        uses: zephyrproject-rtos/action-zephyr-setup@v1
+        with:
+          app-path: zephyr-rust-lang
+          manifest-file-name: ci-manifest.yml
+          toolchains: arm-zephyr-eabi:riscv64-zephyr-elf
+
+      - name: Install Rust Targets
+        shell: bash
+        run: |
+          rustup target add thumbv7em-none-eabi
+          rustup target add thumbv7m-none-eabi
+
+      - name: Setup cargo build
+        working-directory: zephyr-rust-lang
+        run: |
+          # Must do full build
+          west build -b nrf52840dk/nrf52840 docgen
+
+      - name: Build Rust documentation
+        working-directory: zephyr-rust-lang/docgen
+        run: |
+          rm -rf .cargo
+          mkdir .cargo
+          cd .cargo
+          ln -s ../../build/rust/sample-cargo-config.toml config.toml
+          cd ..
+          cargo doc
+
+       - name: Deploy docs to GitHub Pages for pull requests
+         if: github.event_name == 'pull_request'
+         uses: peaceiris/actions-gh-pages@v3
+         with:
+           github_token: ${{ secrets.GITHUB_TOKEN }}
+           publish_dir: ./zephyr-rust-lang/build/rust/target/thumbv7em-none-eabi/doc
+           publish_branch: gh-pages
+           destination_dir: pr-${{ github.event.number }}
+
+        #    - name: Deploy docs to GitHub Pages for push to main
+        #      if: github.event_name == 'push'
+        #      uses: peaceiris/actions-gh-pages@v3
+        #      with:
+        #        github_token: ${{ secrets.GITHUB_TOKEN }}
+        #        publish_dir: ./target/doc
+        #        publish_branch: gh-pages