Minor tweaks to release note (#2182)

* Minor tweaks

* Update CHANGELOG.md

* Update CHANGELOG.md

Author: alexg33

Firestore/CHANGELOG.md

@@ -2,10 +2,11 @@
 
 # v0.16.1
 - [fixed] Offline persistence now properly records schema downgrades. This is a
-  forward-looking change that allows versions past this one to safely downgrade
-  to this version. Downgrading to versions prior this one can be safe depending
-  on the source version. For example, downgrading from v0.16.1 to v0.15.0 is
-  safe because there have been no schema changes between these releases.
+  forward-looking change that allows all subsequent versions to safely downgrade
+  to this version. Some other versions might be safe to downgrade to, if you can
+  determine there haven't been any schema migrations between them. For example,
+  downgrading from v0.16.1 to v0.15.0 is safe because there have been no schema
+  changes between these releases.
 - [fixed] Fixed an issue where gRPC would crash if shut down multiple times
   (#2146).