docs: proc.rst: mountinfo: improved field numbering

Without reading thoroughly, one could easily oversee that there may be several
fields after #6.
Made it more clearly by changing the field numbering.

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>
Link: https://lore.kernel.org/r/20211007040001.103413-2-mail@christoph.anton.mitterer.name
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/proc.rst

@@ -1857,19 +1857,19 @@ For example::
 This file contains lines of the form::
 
     36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
-    (1)(2)(3)   (4)   (5)      (6)      (7)   (8) (9)   (10)         (11)
+    (1)(2)(3)   (4)   (5)      (6)     (n…m) (m+1)(m+2) (m+3)         (m+4)
 
     (1) mount ID:  unique identifier of the mount (may be reused after umount)
     (2) parent ID:  ID of parent (or of self for the top of the mount tree)
     (3) major:minor:  value of st_dev for files on filesystem
     (4) root:  root of the mount within the filesystem
     (5) mount point:  mount point relative to the process's root
     (6) mount options:  per mount options
-    (7) optional fields:  zero or more fields of the form "tag[:value]"
-    (8) separator:  marks the end of the optional fields
-    (9) filesystem type:  name of filesystem of the form "type[.subtype]"
-    (10) mount source:  filesystem specific information or "none"
-    (11) super options:  per super block options
+    (n…m) optional fields:  zero or more fields of the form "tag[:value]"
+    (m+1) separator:  marks the end of the optional fields
+    (m+2) filesystem type:  name of filesystem of the form "type[.subtype]"
+    (m+3) mount source:  filesystem specific information or "none"
+    (m+4) super options:  per super block options
 
 Parsers should ignore all unrecognised optional fields.  Currently the
 possible optional fields are: