docs: counter: Fix spelling

"Miscellaneous" is the correct spelling.
Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/880c2fd0e2e91b8962c9d388b37ba582d548db8e.1623201081.git.vilhelm.gray@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/driver-api/generic-counter.rst

@@ -307,7 +307,7 @@ Determining the type of extension to create is a matter of scope.
 
 * Device extensions are attributes that expose information/control
   non-specific to a particular Count or Signal. This is where you would
-  put your global features or other miscellanous functionality.
+  put your global features or other miscellaneous functionality.
 
   For example, if your device has an overtemp sensor, you can report the
   chip overheated via a device extension called "error_overtemp":