Update release documentation.
Update release documentation.

Reviewers: junius, O1 Material components iOS

Reviewed By: junius, O1 Material components iOS

Tags: #material_components_ios

Differential Revision: http://codereview.cc/D906

brianjmoore/material-components-ios,material-components/material-components-ios,willlarche/material-components-ios,sigito/material-components-ios,brianjmoore/material-components-ios,randallli/material-components-ios,samnm/material-components-ios,Eccelor/material-components-ios,Eccelor/material-components-ios,willlarche/material-components-ios,randallli/material-components-ios,sigito/material-components-ios,randallli/material-components-ios,brianjmoore/material-components-ios,material-components/material-components-ios,randallli/material-components-ios,samnm/material-components-ios,chriscox/material-components-ios,brianjmoore/material-components-ios,samnm/material-components-ios,willlarche/material-components-ios,Eccelor/material-components-ios,Eccelor/material-components-ios,brianjmoore/material-components-ios,chriscox/material-components-ios,chriscox/material-components-ios,Eccelor/material-components-ios,material-components/material-components-ios,randallli/material-components-ios,willlarche/material-components-ios,sigito/material-components-ios,randallli/material-components-ios,material-components/material-components-ios,willlarche/material-components-ios,chriscox/material-components-ios,chriscox/material-components-ios,sigito/material-components-ios,material-components/material-components-ios,samnm/material-components-ios,sigito/material-components-ios,samnm/material-components-ios