doc/cephfs: edit "is mount helper present"

Edit the section called "Is mount helper present?", the title of which
prior to this commit was "Is mount helper is present?". Other small
disambiguating improvements have been made to the text in the section.
An unselectable prompt has been added before a command.

Signed-off-by: Zac Dover <[email protected]>

Author: zdover23

doc/cephfs/mount-using-kernel-driver.rst

@@ -20,16 +20,18 @@ Complete General Prerequisites
 Go through the prerequisites required by both, kernel as well as FUSE mounts,
 in `Mount CephFS: Prerequisites`_ page.
 
-Is mount helper is present?
----------------------------
+Is mount helper present?
+------------------------
 ``mount.ceph`` helper is installed by Ceph packages. The helper passes the
-monitor address(es) and CephX user keyrings automatically saving the Ceph
-admin the effort to pass these details explicitly while mounting CephFS. In
-case the helper is not present on the client machine, CephFS can still be
-mounted using kernel but by passing these details explicitly to the ``mount``
-command. To check whether it is present on your system, do::
+monitor address(es) and CephX user keyrings, saving the Ceph admin the effort
+of passing these details explicitly while mounting CephFS. If the helper is not
+present on the client machine, CephFS can still be mounted using the kernel
+driver, but only by passing these details explicitly to the ``mount`` command.
+To check whether ``mount.ceph`` is present on your system, run the following command:
 
-    stat /sbin/mount.ceph
+.. prompt:: bash #
+
+   stat /sbin/mount.ceph
 
 Which Kernel Version?
 ---------------------