fix(docs): pin builddocs to 1.x to fix api docs build

builddocs 2.x is an incompatible rewrite: the `build()` function was
replaced by `buildDocs()`, which emits HTML and drops the markdown
output and template support the docs script relies on. #2404 bumped it
from ^1.0.8 to ^2.0.0, breaking `pnpm -F @milkdown/docs run build`
with "import_builddocs.build is not a function".

Pin back to ^1.0.9 and add a renovate rule to block builddocs major
upgrades until the script is migrated.

Author: Saul-Mirone

.github/renovate.json

@@ -19,6 +19,12 @@
       "matchDepNames": ["prosemirror-*"],
       "groupName": "prosemirror"
     },
+    {
+      "matchDepNames": ["builddocs"],
+      "description": "builddocs 2.x is an incompatible rewrite (HTML output, no markdown/templates); stay on 1.x",
+      "matchUpdateTypes": ["major"],
+      "enabled": false
+    },
     {
       "groupName": "all non-major dependencies",
       "groupSlug": "all-minor-patch",

docs/package.json

@@ -15,7 +15,7 @@
   },
   "devDependencies": {
     "@types/fs-extra": "^11.0.4",
-    "builddocs": "^2.0.0",
+    "builddocs": "^1.0.9",
     "fs-extra": "^11.3.0"
   }
 }