Update Builder Codes to include Coming Soon (#669)

* Add builder code docs

* Update docs/base-chain/quickstart/builder-codes.mdx

Co-authored-by: Conner Swenberg <cls364@cornell.edu>

* update to use only builder code

* update to coming soon with callout at the top of the document

---------

Co-authored-by: Conner Swenberg <cls364@cornell.edu>

Author: ericbrown99

docs/base-chain/quickstart/builder-codes.mdx

@@ -1,8 +1,13 @@
 ---
-title: "Builder Codes"
+title: "Builder Codes (coming soon)" 
+sidebarTitle: "Builder Codes"
 description: "Integrate Builder Codes to attribute onchain activity to your app or wallet."
 ---
 
+<Warning>
+Base will issue Builder Codes out of Base.dev starting **in early December**. We've released these docs ahead of launch to give teams time to understand implementation.
+</Warning>
+
 Builder Codes allow you to attribute onchain activity to your app or wallet, unlocking analytics, rewards, and future incentives. This guide covers the implementation steps for both application developers and wallet providers.
 
 ## For App Developers