README.md: new release
Not much has changed, but dep users are complaining about the breaking
due to protobuf changes.
@@ -33,6 +33,17 @@ make backwards-incompatible changes.
## News
+_May 18, 2018_
+
+*v0.23.0*
+
+- bigquery: Add DDL stats to query statistics.
+- bigtable:
+ - cbt: Add cells-per-column limit for row lookup.
+ - cbt: Make it possible to combine read filters.
+- dlp: v2beta2 client removed. Use the v2 client instead.
+- firestore, spanner: Fix compilation errors due to protobuf changes.
+
_May 8, 2018_
*v0.22.0*
