github: Add workflow to build and deploy docs

This builds the gcov coverage report and the skiboot docs on the Github
hosted runner, without using a container.

Remove the CROSS= definition from build-docs.sh to allow the makefile
detect which cross compiler is installed, instead of hardcoding the
non-le variant.

This is a simplification from the previous docs build, which used the
containers. However the containers have since been re-worked and no
longer leave the build artifacts on the host system.

The github action used for deploying seems to be the most commonly used:

 https://github.com/JamesIves/github-pages-deploy-action

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

.github/workflows/build-docs.yml

+name: Generate and deploy documentation
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  docs-build-and-deploy:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Install apt dependencies
+        run: |
+          sudo apt install -qq build-essential gcc-powerpc64le-linux-gnu git lcov \
+          device-tree-compiler libssl-dev libmbedtls-dev \
+          python3-sphinx python3-recommonmark
+
+      - name: Generate docs and coverage report
+        run: ./opal-ci/build-docs.sh
+
+      - name: Deploy docs
+        uses: JamesIves/github-pages-deploy-action@v4.2.5
+        with:
+          branch: gh-pages
+          folder: doc/_build/ghpages

opal-ci/build-docs.sh

@@ -5,7 +5,6 @@ set -e
 set -vx
 
 MAKE_J=$(grep -c processor /proc/cpuinfo)
-export CROSS="ccache powerpc64-linux-gnu-"
 
 make -j${MAKE_J} SKIBOOT_GCOV=1 coverage-report