doc: Remove redundant words
doc: Remove redundant words

Fixes: 400038f6cac9 ("include: Add a group for mock objects.")
Signed-off-by: Alexander Dahl <e4ea294c062c525643df036a35ca579b905fa400@thorsis.com>
Reviewed-by: Andreas Schneider <5be00ddc76278cf6077f5047ca3384a88460c671@cryptomilk.org>
clibs/cmocka,clibs/cmocka