docs: Sort sections on qemu-img subcommand parameters

We already list the subcommand summaries alphabetically, we should do
the same for the documentation related to subcommand-specific
parameters.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200513011648.166876-2-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

docs/tools/qemu-img.rst

@@ -142,30 +142,6 @@ by the used format or see the format descriptions below for details.
   the documentation of the emulator's ``-drive cache=...`` option for allowed
   values.
 
-Parameters to snapshot subcommand:
-
-.. program:: qemu-img-snapshot
-
-.. option:: snapshot
-
-  Is the name of the snapshot to create, apply or delete
-
-.. option:: -a
-
-  Applies a snapshot (revert disk to saved state)
-
-.. option:: -c
-
-  Creates a snapshot
-
-.. option:: -d
-
-  Deletes a snapshot
-
-.. option:: -l
-
-  Lists all snapshots in the given image
-
 Parameters to compare subcommand:
 
 .. program:: qemu-img-compare
@@ -245,6 +221,30 @@ Parameters to dd subcommand:
 
   Sets the number of input blocks to skip
 
+Parameters to snapshot subcommand:
+
+.. program:: qemu-img-snapshot
+
+.. option:: snapshot
+
+  Is the name of the snapshot to create, apply or delete
+
+.. option:: -a
+
+  Applies a snapshot (revert disk to saved state)
+
+.. option:: -c
+
+  Creates a snapshot
+
+.. option:: -d
+
+  Deletes a snapshot
+
+.. option:: -l
+
+  Lists all snapshots in the given image
+
 Command description:
 
 .. program:: qemu-img-commands