Add preview of docs

Author: devmotion

.github/workflows/DocsPreviewCleanup.yml

@@ -0,0 +1,26 @@
+name: Docs Preview Cleanup
+
+on:
+  pull_request:
+    types: [closed]
+
+jobs:
+  docs-preview-cleanup:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout gh-pages branch
+        uses: actions/checkout@v2
+        with:
+          ref: gh-pages
+      - name: Delete preview and history + push changes
+        run: |
+            if [ -d "previews/PR$PRNUM" ]; then
+              git config user.name "Documenter.jl"
+              git config user.email "[email protected]"
+              git rm -rf "previews/PR$PRNUM"
+              git commit -m "delete preview"
+              git branch gh-pages-new $(echo "delete history" | git commit-tree HEAD^{tree})
+              git push --force origin gh-pages-new:gh-pages
+            fi
+        env:
+            PRNUM: ${{ github.event.number }}

docs/make.jl

@@ -17,4 +17,4 @@ makedocs(modules=[DiffRules],
          checkdocs=:exports,
 )
 
-deploydocs(repo = "github.com/JuliaDiff/DiffRules.jl")
+deploydocs(; repo="github.com/JuliaDiff/DiffRules.jl", push_preview=true)