README.md: new release

Not much has changed, but dep users are complaining about the breaking
due to protobuf changes.

Change-Id: If22cd90f18c94d0c014b6cd74d5018b0364cb1ac
Reviewed-on: https://code-review.googlesource.com/27830
Reviewed-by: Jean de Klerk <deklerk@google.com>
diff --git a/README.md b/README.md
index ab14578..ac66000 100644
--- a/README.md
+++ b/README.md
@@ -33,6 +33,17 @@
 
 ## 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*