[docs][release] Merge stable Changelog to main and update broken links.

Change-Id: Iba25e89e98332ccd8b0f4e18213cebc39bbe7f0b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/326141
Reviewed-by: William Hesse <[email protected]>
Commit-Queue: Kevin Chisholm <[email protected]>

Author: itsjustkevin

CHANGELOG.md

@@ -201,6 +201,37 @@ constraint][language version] lower bound to 3.2 or greater (`sdk: '^3.2.0'`).
   changed between direct, dev and transitive dependency.
 - The command `dart pub upgrade` no longer shows unchanged dependencies.
 
+## 3.1.2 - 2023-09-13
+
+This is a patch release that:
+
+- Fixes a bug in dart2js which crashed the compiler when a typed record pattern
+  was used outside the scope of a function body, such as in a field initializer.
+  For example `final x = { for (var (int a,) in someList) a: a };`
+  (issue [#53449])
+
+- Fixes an expedient issue of users seeing an unhandled
+  exception pause in the debugger, please see
+  https://github.com/dart-lang/sdk/issues/53450 for more
+  details.
+  The fix uses try/catch in lookupAddresses instead of
+  Future error so that we don't see an unhandled exception
+  pause in the debugger (issue [#53450])
+
+[#53449]: https://github.com/dart-lang/sdk/issues/53449
+[#53450]: https://github.com/dart-lang/sdk/issues/53450
+
+## 3.1.1 - 2023-09-07
+
+This is a patch release that:
+
+- Fixes a bug in the parser which prevented a record pattern from containing a
+  nested record pattern, where the nested record pattern uses record
+  destructuring shorthand syntax, for example `final ((:a, :b), c) = record;`
+  (issue [#53352]).
+
+[#53352]: https://github.com/dart-lang/sdk/issues/53352
+
 ## 3.1.0
 
 ### Libraries