input: Docs: correct ntrig.rst typo

Fix a typo in ntrig.rst (found with 'codespell').

Signed-off-by: Randy Dunlap <[e-mail]>
Cc: Dmitry Torokhov <[e-mail]>
Cc: [e-mail]
Cc: Jonathan Corbet <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/input/devices/ntrig.rst

···
 |activation_height,	|size threshold to activate immediately		      |
 |activation_width	|						      |
 +-----------------------+-----------------------------------------------------+
-|min_height,		|size threshold bellow which fingers are ignored      |
+|min_height,		|size threshold below which fingers are ignored       |
 |min_width		|both to decide activation and during activity	      |
 +-----------------------+-----------------------------------------------------+
 |deactivate_slack	|the number of "no contact" frames to ignore before   |