lables: use labels instead of annotation in the description of labels

Signed-off-by: Lei Jitang <[email protected]>

Author: coolljt0725

config.md

@@ -136,8 +136,8 @@ Note: Any OPTIONAL field MAY also be set to null, which is equivalent to being a
      Keys MUST be unique within this map, and best practice is to namespace the keys.
      Keys SHOULD be named using a reverse domain notation - e.g. `com.example.myKey`.
      Keys using the `org.opencontainers` namespace are reserved and MUST NOT be used by subsequent specifications.
-     If there are no annotations then this property MAY either be absent or an empty map.
-     Implementations that are reading/processing this configuration file MUST NOT generate an error if they encounter an unknown annotation key.
+     If there are no labels then this property MAY either be absent or an empty map.
+     Implementations that are reading/processing this configuration file MUST NOT generate an error if they encounter an unknown labels key.
 
 - **rootfs** *object*, REQUIRED