rbd: update man page to avoid deprecated --secret, --user

Signed-off-by: Sage Weil <[email protected]>

doc/man/8/rbd.rst

@@ -54,13 +54,20 @@ Parameters
 
    Specifies the snapshot name for the specific operation.
 
-.. option:: --user username
+.. option:: --id username
 
-   Specifies the username to use with the map command.
+   Specifies the username (without the ``client.'' prefix) to use with the map command.
 
-.. option:: --secret filename
+.. option:: --keyfile filename
 
    Specifies a file containing the secret to use with the map command.
+   If not specified, ``client.admin'' will be used by default.
+
+.. option:: --keyring filename
+
+   Specifies a keyring file containing a secret for the specified user
+   to use with the map command.  If not specified, the default keyring
+   locations will be searched.
 
 
 Commands
@@ -170,7 +177,7 @@ To delete a snapshot::
 
 To map an image via the kernel with cephx enabled::
 
-       rbd map myimage --user admin --secret secretfile
+       rbd map myimage --id admin --keyfile secretfile
 
 To unmap an image::