"To add that capability" means to improve or upgrade something by including a particular feature, skill, or function that was not previously present. Full definition
This is a serious, high - performance industrial bar code printer that has added capability of printing in full - colour. (primeralabel.eu)
And vertical images appear as small versions presented in horizontal mode; RIM said it will add that capability in a future update. (computerworld.com)
He also added capabilities to inject custom messages as needed. (developer.amazon.com)