message: Update changelog notes with more information about the fix.
diff: ### Bugfixes
  * Fixed an assertion on a corner case of reallocation on large arrays.
  + PR [#2500](https://github.com/realm/realm-core/pull/2500).
  + Fixes issue [#2451](https://github.com/realm/realm-core/issues/2451).
  ### Breaking changes
  