Scope search to only WSL docs

Author: mattwojo

WSL/docfx.json

@@ -39,6 +39,7 @@
       "ms.technology": "windows-subsystem-for-linux",
       "author": "craigloewen-msft",
       "ms.author": "crloewen",
+      "searchScope": ["WSL"],
       "feedback_product_url": "https://github.com/Microsoft/WSL/issues"
     },
     "fileMetadata": {},