feat: generate vim docs on push with a github action

.github/workflows/doc.yml

@@ -0,0 +1,16 @@
+name: docs
+
+on: [push]
+
+jobs:
+  docs:
+    runs-on: ubuntu-latest
+    name: pandoc to vimdoc
+    steps:
+      - uses: actions/checkout@v2
+      - name: panvimdoc
+        uses: kdheepak/panvimdoc@main
+        with:
+          vimdoc: scalpel.nvim
+          toc: true
+          treesitter: true