HADOOP-13497. fix wrong command in CredentialProviderAPI.md. Contributed by Yuanbo Liu.

(cherry picked from commit 8aae8d6bf03ade0607547ed461dc99a336a7e9d4)

hadoop-common-project/hadoop-common/src/site/markdown/CredentialProviderAPI.md

@@ -119,7 +119,7 @@ See the command options detail in the [Commands Manual](CommandsManual.html#cred
 
 Utilizing the credential command will often be for provisioning a password or secret to a particular credential store provider. In order to explicitly indicate which provider store to use the `-provider` option should be used.
 
-Example: `hadoop credential create ssl.server.keystore.password jceks://file/tmp/test.jceks`
+Example: `hadoop credential create ssl.server.keystore.password -provider jceks://file/tmp/test.jceks`
 
 In order to indicate a particular provider type and location, the user must provide the `hadoop.security.credential.provider.path` configuration element in core-site.xml or use the command line option `-provider` on each of the credential management commands. This provider path is a comma-separated list of URLs that indicates the type and location of a list of providers that should be consulted. For example, the following path: `user:///,jceks://file/tmp/test.jceks,jceks://hdfs@nn1.example.com/my/path/test.jceks` indicates that the current user's credentials file should be consulted through the User Provider, that the local file located at `/tmp/test.jceks` is a Java Keystore Provider and that the file located within HDFS at `nn1.example.com/my/path/test.jceks` is also a store for a Java Keystore Provider.