[kv-interface] Add Readme.md

Author: wangzk

java/kvstore-interface/Readmd.md

@@ -0,0 +1,12 @@
+# KVStore interface
+
+## Change log
+
+### 1.2.1
+
+Fix the data race in the counters in the cached client.
+
+
+### 1.2
+
+Change the configuration item in the cache from `cache.capacity.in.gbytes` to `cache.capacity.in.byte`.