kv.proto: docs of create_revision, mod_revision

storage/storagepb/kv.proto

@@ -11,8 +11,9 @@ option (gogoproto.goproto_enum_prefix_all) = false;
 
 message KeyValue {
   bytes key = 1;
+  // create_revision is the revision of last creation on this key.
   int64 create_revision = 2;
-  // mod_revision is the last modified revision of the key.
+  // mod_revision is the revision of last modification on this key.
   int64 mod_revision = 3;
   // version is the version of the key. A deletion resets
   // the version to zero and any modification of the key