Update changelog

Author: wilhuff

Firestore/CHANGELOG.md

@@ -4,6 +4,12 @@
   improvements. This benefit is reduced if changes accumulate while the query
   is inactive. Queries that use the `limit()` API may not always benefit,
   depending on the accumulated changes.
+- [changed] Changed the location of Firestore's locally stored data from the
+  Documents folder to Library/Application Support, hiding it from users of apps
+  that share their files with the iOS Files app. **Important** Older versions
+  of the Firestore SDK can't read data from the new location, so once user data
+  has been migrated to the new folder, downgrading to an older version will
+  cause that user to appear to lose data.
 
 # v1.9.0
 - [feature] Added a `limit(toLast:)` query operator, which returns the last
@@ -43,7 +49,7 @@
   experience.
 
 # v1.6.1
-- [fixed] Fix a race condition that could cause a segmentation fault during
+- [fixed] Fixed a race condition that could cause a segmentation fault during
   client initialization.
 
 # v1.6.0