chore(docs): use gh action to build docs (#8097)

# Which Problems Are Solved

This allows us to build multiple docs in parallel and only runs when
docs/proto are changed.

# Additional Changes

- [ ] Change "required" in GitHub from Vercel to the docs flow

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>

docs/vercel.json

@@ -1,4 +1,7 @@
 {
+    "github": {
+        "enabled": false
+      },
     "cleanUrls": true,
     "rewrites": [
         {