doc: update AsyncResource.bind doc to reflect new thisArg behaviour

Author: rochdev

doc/api/async_context.md

@@ -446,6 +446,9 @@ added:
   - v14.8.0
   - v12.19.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/42177
+    description: Changed the default when `thisArg` is not provided to use `this` from the caller.
   - version: v16.0.0
     pr-url: https://github.com/nodejs/node/pull/36782
     description: Added optional thisArg.
@@ -468,6 +471,9 @@ added:
   - v14.8.0
   - v12.19.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/42177
+    description: Changed the default when `thisArg` is not provided to use `this` from the caller.
   - version: v16.0.0
     pr-url: https://github.com/nodejs/node/pull/36782
     description: Added optional thisArg.