all: release v0.16.0

This commit will be tagged v0.16.0.

Change-Id: I83356570a15bbe6562171723e79913ffb7c6a808
Reviewed-on: https://code-review.googlesource.com/c/google-api-go-client/+/50572
Reviewed-by: Tyler Bui-Palsulich <tbp@google.com>

Author: broady

CHANGES.md

@@ -1,3 +1,18 @@
+# v0.16.0
+
+- Increase the default chunk size for uploads (e.g., for the storage package) to 16 MB.
+
+- transport:
+  - Automatically populate QuotaProject from the "quota_project_id" field in the JSON credentials file.
+  - Add grpc.DialPool, which opens multiple grpc.ClientConns based on WithGRPCConnectionPool option.
+
+- Added a check to prevent mixed calls to Add and AddWait.
+
+- Various updates to autogenerated clients.
+
+_Please note:_ the release version is not indicative of an individual client's
+stability or version.
+
 # v0.15.0
 
 - monitoring/v3: