Remove typo in README.
Remove typo in README.

mageekguy/atoum,mikaelrandy/atoum,jubianchi/atoum,tejerka/atoum,jubianchi/atoum,Tiross/atoum,agallou/atoum,agallou/atoum,CedCannes/atoum,vonglasow/atoum,mikaelrandy/atoum,GuillaumeDievart/atoum,mageekguy/atoum,GuillaumeDievart/atoum,Tiross/atoum,gpaton/atoum,gpaton/atoum,vonglasow/atoum,CedCannes/atoum,tejerka/atoum