fix typo in document

library/packaging/rpm_key

@@ -46,13 +46,13 @@ options:
 
 EXAMPLES = '''
 # Example action to import a key from a url
-- rpm_key state=present key=http://apt.sw.be/RPM-GPG-KEY.dag.txt
+- rpm_key: state=present key=http://apt.sw.be/RPM-GPG-KEY.dag.txt
 
 # Example action to import a key from a file
-- rpm_key state=present key=/path/to/key.gpg
+- rpm_key: state=present key=/path/to/key.gpg
 
 # Example action to ensure a key is not present in the db
-- rpm_key state=absent key=DEADB33F
+- rpm_key: state=absent key=DEADB33F
 '''
 import syslog
 import os.path