Add GitHub Actions (#496)

* Add Github actions

Using bot's mail looks better in the wiki, since in main page it shows the pusher name but in the revisions tab it shows the bot.

Allow failure is to prevent the commit appearing with a cross just because the wiki didn't change. It can probably also be fixed in the command part, but does the same

* Rules-to-wiki 1.0

.github/workflows/merge-docs.yml

@@ -0,0 +1,19 @@
+name: Merge docs
+on:
+  push:
+    paths:
+    - "docs/**"
+    - "!docs/scarpet/Full.md"
+jobs:
+  Scarpet:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Merge docs
+        run: ./mergedoc.sh
+      - name: Commit merged docs
+        run: |
+          git config --global user.name 'github-actions[bot]'
+          git config --global user.email 'github-actions[bot]@users.noreply.github.com'
+          git commit -am "Merge docs for '${{ github.event.head_commit.message }}'"
+          git push