devlink: remove trigger command from devlink-region.rst

The devlink trigger command does not exist. While rewriting the
documentation for devlink into the reStructuredText format,
documentation for the trigger command was accidentally merged in. This
occurred because the author was also working on a potential extension to
devlink regions which included this trigger command, and accidentally
squashed the documentation incorrectly.

Further review eventually settled on using the previously unused "new"
command instead of creating a new trigger command.

Fix this by removing mention of the trigger command from the
documentation.

Fixes: 0b0f945f ("devlink: add a file documenting devlink regions", 2020-01-10)
Noticed-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NJacob Keller <jacob.e.keller@intel.com>
Reviewed-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Documentation/networking/devlink/devlink-region.rst

@@ -40,9 +40,6 @@ example usage
     # Delete a snapshot using:
     $ devlink region del pci/0000:00:05.0/cr-space snapshot 1
 
-    # Trigger (request) a snapshot be taken:
-    $ devlink region trigger pci/0000:00:05.0/cr-space
-
     # Dump a snapshot:
     $ devlink region dump pci/0000:00:05.0/fw-health snapshot 1
     0000000000000000 0014 95dc 0014 9514 0035 1670 0034 db30