Update 602 Release Notes.

Author: amritpan

Release Notes/602.md

@@ -25,6 +25,12 @@
   - Pull Request: https://github.com/swiftlang/swift-syntax/pull/2925
   - Migration steps: Use `SyntaxChildren.endIndex` instead.
   - Notes: `ExpressibleByNilLiteral` was a mistake. In general, `Collection.Index` should only be created and managed by the collection itself. For example, `Collection.index(after:)` exists, but `Index.advanced(by:)` does not.
+  
+  - *Affected API or two word description*
+  - Description: *A new keypath component (`.keyPathMethodComponent`) has been added to handle fully applied keypath methods and initializers.*
+  - Pull Request: *https://github.com/swiftlang/swift-syntax/pull/2950*
+  - Migration steps: To switch over KeyPathComponent.Component exhaustively, please add handling for `.keyPathMethodComponent`.
+  - Notes: Keypath methods and initializers are an uncoming Swift language feature.
 
 ## Template