[docs] charter: link the accepted BiDi support boundary record (#17928)

17670 was accepted on 2026-07-23; the charter states each decision is
marked ADR pending until its record is accepted, at which point the
charter links it.

Author: AutomatedTester

docs/plans/selenium-5.md

@@ -19,7 +19,7 @@ it. An ADR does not name a milestone; this charter records what belongs to Selen
 
 ## Required for release
 
-### BiDi support boundary — _ADR pending_
+### BiDi support boundary — [17670](../decisions/17670-bidi-implementation-boundaries.md)
 
 How the WebDriver BiDi protocol is exposed to users across the bindings. The ADR sets where the
 boundary sits between supported Selenium API and internal implementation, and how each binding