documentation: zonefs: Cleanup the mount options section

Use subsections to separate the descriptions of the "error=" and
"explicit-open" mount sections.

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>

Documentation/filesystems/zonefs.rst

@@ -306,8 +306,15 @@ Further notes:
 Mount options
 -------------
 
-zonefs define the "errors=<behavior>" mount option to allow the user to specify
+zonefs defines several mount options:
-zonefs behavior in response to I/O errors, inode size inconsistencies or zone
+* errors=<behavior>
+* explicit-open
+
+"errors=<behavior>" option
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The "errors=<behavior>" option mount option allows the user to specify zonefs
+behavior in response to I/O errors, inode size inconsistencies or zone
 condition changes. The defined behaviors are as follow:
 
 * remount-ro (default)
@@ -326,6 +333,9 @@ discover the amount of data that has been written to the zone. In the case of a
 read-only zone discovered at run-time, as indicated in the previous section.
 The size of the zone file is left unchanged from its last updated value.
 
+"explicit-open" option
+~~~~~~~~~~~~~~~~~~~~~~
+
 A zoned block device (e.g. an NVMe Zoned Namespace device) may have limits on
 the number of zones that can be active, that is, zones that are in the
 implicit open, explicit open or closed conditions.  This potential limitation