Update React Native documentation (0.21)
Update React Native documentation (0.21)

yosiat/devdocs,abougouffa/devdocs,webcoding/devdocs,yosiat/devdocs,hyjk2000/devdocs,mnquintana/devdocs,rlugojr/devdocs,webcoding/devdocs,abougouffa/devdocs,webcoding/devdocs,hyjk2000/devdocs,yosiat/devdocs,mnquintana/devdocs,rlugojr/devdocs,rlugojr/devdocs