Swift: Add to change note.

geoffw0 · geoffw0 · commit eb78d401da0b · 2023-09-26T14:56:32.000+01:00
diff --git a/swift/ql/lib/change-notes/2023-09-26-regex-mode-flags.md b/swift/ql/lib/change-notes/2023-09-26-regex-mode-flags.md
@@ -1,4 +1,4 @@
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 category: minorAnalysis
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-* The regular expressions library now accepts a wider range of mode flags in a regular expression mode flag group (such as `(?u)`).
+* The regular expressions library now accepts a wider range of mode flags in a regular expression mode flag group (such as `(?u)`). The `(?w`) flag has been renamed from "UNICODE" to "UNICODEBOUNDARY", and the `(?u)` flag is called "UNICODE" in the libraries.
