cephfs: document using multiple fs on Windows

This change updates the ceph-dokan documentation, showing how
a non-default Ceph filesystem can be mounted.

Fixes: https://tracker.ceph.com/issues/49662
Signed-off-by: Lucian Petrut <lpetrut@cloudbasesolutions.com>

doc/cephfs/ceph-dokan.rst

@@ -42,6 +42,9 @@ and :ref:`User Management <user-management>`.
 Usage
 =====
 
+Mounting filesystems
+--------------------
+
 In order to mount a ceph filesystem, the following command can be used::
 
     ceph-dokan.exe -c c:\ceph.conf -l x
@@ -61,16 +64,29 @@ changed using the following ``ceph.conf`` options::
     client_mount_uid = 1000
     client_mount_gid = 1000
 
+If you have more than one FS on your Ceph cluster, use the option
+``--client_fs`` to mount the non-default FS::
+
+    mkdir -Force C:\mnt\mycephfs2
+    ceph-dokan.exe --mountpoint C:\mnt\mycephfs2 --client_fs mycephfs2
+
+CephFS subdirectories can be mounted using the ``--root-path`` parameter::
+
+    ceph-dokan -l y --root-path /a
+
+If the ``-o --removable`` flags are set, the mounts will show up in the
+``Get-Volume`` results::
+
+    PS C:\> Get-Volume -FriendlyName "Ceph*" | `
+            Select-Object -Property @("DriveLetter", "Filesystem", "FilesystemLabel")
+
+    DriveLetter Filesystem FilesystemLabel
+    ----------- ---------- ---------------
+              Z Ceph       Ceph
+              W Ceph       Ceph - new_fs
+
 Please use ``ceph-dokan --help`` for a full list of arguments.
 
-The mount can be removed by either issuing ctrl-c or using the unmap command,
-like so::
-
-    ceph-dokan.exe unmap -l x
-
-Note that when unmapping Ceph filesystems, the exact same mountpoint argument
-must be used as when the mapping was created.
-
 Credentials
 -----------
 
@@ -80,6 +96,17 @@ use for mounting CephFS. The following commands are equivalent::
     ceph-dokan --id foo -l x
     ceph-dokan --name client.foo -l x
 
+Unmounting filesystems
+----------------------
+
+The mount can be removed by either issuing ctrl-c or using the unmap command,
+like so::
+
+    ceph-dokan.exe unmap -l x
+
+Note that when unmapping Ceph filesystems, the exact same mountpoint argument
+must be used as when the mapping was created.
+
 Limitations
 -----------