set up Github Action CI

.github/workflows/docs.yml

@@ -0,0 +1,40 @@
+name: Documentation
+
+on:
+  pull_request:
+  push:
+    branches:
+      - 'master'
+      - 'release-'
+    tags: '*'
+  release:
+    types: published
+
+jobs:
+  build_html:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install dependencies
+        run: julia --project=docs/ -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate()'
+      - name: Build and deploy
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }}
+        run: |
+          julia -e 'include("contrib/build_sysimg.jl"); build_sysimg(force=true)'
+          julia --project=doc/ doc/make.jl deploy
+  build_pdf:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Build and deploy
+        uses: docker://tianjun2018/documenter-latex:latest
+        run: |
+          apt-get update -q && apt-get install python3-pip -yq
+          pip3 install jill && jill install --confirm
+          julia -e 'using InteractiveUtils; versioninfo()'
+          ls -al
+          julia --project=doc/ -e 'using Pkg; Pkg.develop(PacakageSpec(path=pwd())); Pkg.instantiate()'
+          julia --project=doc/ doc/make.jl pdf texplatform=native
+