firestore: release firestore/1.1.1

Change-Id: I96b49f451a829651de0b4a388649df24402012ae
Reviewed-on: https://code-review.googlesource.com/c/gocloud/+/49230
Reviewed-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: BenWhitehead <benwhitehead@google.com>
Reviewed-by: Jean de Klerk <deklerk@google.com>
diff --git a/firestore/CHANGES.md b/firestore/CHANGES.md
index 1b8fdc2..92381af 100644
--- a/firestore/CHANGES.md
+++ b/firestore/CHANGES.md
@@ -1,5 +1,9 @@
 # Changes
 
+## v1.1.1
+
+- Fix bug in CollectionGroup query validation.
+
 ## v1.1.0
 
 - Add support for `in` and `array-contains-any` query operators.