doc: fix misspelling in userspace doc

fix misspelling

Signed-off-by: David B. Kinder <[email protected]>

Author: dbkinder

samples/userspace/prod_consumer/README.rst

@@ -46,7 +46,7 @@ The control loop is as follows:
  - Application B processing thread waits on new items in the queue. It
    then processes the data in-place, and after it's finished it places
    the processed data into another queue to be written back to the driver.
- - Applicarion A writeback thread monitors the outgoing data queue for
+ - Application A writeback thread monitors the outgoing data queue for
    new items containing processed data. As it gets them it will write
    such data back to the driver and free the buffer.