[llvm][Docs] Add Minidump related LLDB release notes (#122759)

Add some release notes for the Minidump work I did over the last few
months.

Author: Jlalond

llvm/docs/ReleaseNotes.md

@@ -450,6 +450,13 @@ Changes to LLDB
           _regexp-display   -- Evaluate an expression at every stop (see 'h...
   ```
 
+  * Minidumps generated by LLDB now support:
+    * 64 bit memory (due to 64b support, Minidumps are now paged to disk while being written).
+    * Capturing of TLS variables.
+    * Multiple signals or exceptions, including breakpoints.
+
+  * [New Core File API](https://lldb.llvm.org/python_api/lldb.SBSaveCoreOptions.html). This gives greater control on the data captured into the core file, relative to the existing `process save-core` styles.
+
 Changes to BOLT
 ---------------------------------