Fix OpenShift Guidelines link in IMAGES.rst (apache#9978)

IMAGES.rst

@@ -649,7 +649,7 @@ The PROD image entrypoint works as follows:
 * In case the user is not "airflow" (with undefined user id) and the group id of the user is set to 0 (root),
   then the user is dynamically added to /etc/passwd at entry using USER_NAME variable to define the user name.
   This is in order to accommodate the
-  `OpenShift Guidelines<https://docs.openshift.com/enterprise/3.0/creating_images/guidelines.html>`_
+  `OpenShift Guidelines <https://docs.openshift.com/enterprise/3.0/creating_images/guidelines.html>`_
 
 * If ``AIRFLOW__CORE__SQL_ALCHEMY_CONN`` variable is passed to the container and it is either mysql or postgres
   SQL alchemy connection, then the connection is checked and the script waits until the database is reachable.