add an entry to the changelog (#998)

diff --git a/dwds/CHANGELOG.md b/dwds/CHANGELOG.md
index 0b14797..836b781 100644
--- a/dwds/CHANGELOG.md
+++ b/dwds/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## 3.1.1-dev
 
 - Change the reported names for isolates to be more terse.
+- Implemented the 'PossibleBreakpoints' report kind for `getSourceReport()`.
 - Change the returned errors for the unimplemented `getClassList` and `reloadSources`
   methods to -32601 ('method does not exist / is not available').