Make the rules look a bit nicer

Summary: Give it a custom description. Ugly place to do it, but there really isn't a better place.

Reviewed By: stepancheg

Differential Revision: D44749216

fbshipit-source-id: 0a1781acdb9322fa7a47eddf3515374c00b458d7

docs.py

@@ -82,6 +82,7 @@ def main() -> None:
         )
 
         for orig in Path(tmp).rglob("*.md"):
+            src = read_file(orig)
             x = os.path.relpath(orig, tmp)
             name = Path(x).stem
             if name.endswith(".bzl"):
@@ -91,11 +92,13 @@ def main() -> None:
                 dest = x[7:-3]
             elif x.endswith("/rules.bzl.md"):
                 dest = "rules"
+                prefix += "# Rules\n\nThese rules are available as standard in Buck2.\n"
+                src = "\n".join(src.splitlines()[1:])
             else:
                 dest = x[:-3]
             dest = "docs/api/" + dest + ".generated.md"
             os.makedirs(Path(dest).parent, exist_ok=True)
-            write_file(dest, prefix + read_file(orig))
+            write_file(dest, prefix + src)
 
 
 if __name__ == "__main__":

website/sidebars.js

@@ -177,7 +177,7 @@ const manualSidebar = [
       {
         type: 'doc',
         id: 'api/rules',
-        label: 'Rules API',
+        label: 'Rules',
       },
       {
         type: 'category',