refactor(docs): inline pandoc build into Makefile (#6)

* refactor(docs): inline pandoc build into Makefile, drop scripts dir

* ci(docs): use make target in workflow, drop scripts path trigger

.github/workflows/docs.yml

@@ -5,7 +5,7 @@ on:
     branches: [master]
     paths:
       - "docs/**"
-      - "scripts/build-docs.sh"
+      - "Makefile"
       - ".github/workflows/docs.yml"
   workflow_dispatch:
 
@@ -28,7 +28,7 @@ jobs:
         run: sudo apt-get update && sudo apt-get install -y pandoc
 
       - name: Build site
-        run: ./scripts/build-docs.sh
+        run: make docs
 
       - uses: actions/upload-pages-artifact@v3
         with: