docs: Fix formatting in fedora.rst

Fix rst formatting in fedora.rst so that the commands look correctly
on the web.

Signed-off-by: Yi-Hung Wei <yihung.wei@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

Documentation/intro/install/fedora.rst

@@ -64,10 +64,10 @@ The command below will create a temporary SPEC file::
 
 And to install specific dependencies, use the corresponding tool below.
 For some of the dependencies on RHEL you may need to add two additional
-repositories to help yum-builddep.
+repositories to help yum-builddep, e.g.::
 
-subscription-manager repos --enable=rhel-7-server-extras-rpms
-subscription-manager repos --enable=rhel-7-server-optional-rpms
+    $ subscription-manager repos --enable=rhel-7-server-extras-rpms
+    $ subscription-manager repos --enable=rhel-7-server-optional-rpms
 
 DNF::