Correct release candidate version on README

[daemonsy]

It seems that the version stated on the README cannot be found, but react-select@1.0.0-rc.10 is the latest version.

$ -> npm install react-select@1.0.0-rc --save
npm ERR! code ETARGET
npm ERR! notarget No matching version found for react-select@1.0.0-rc
npm ERR! notarget In most cases you or one of your dependencies are requesting
npm ERR! notarget a package version that doesn't exist.

[coveralls]

Coverage remained the same at 91.994% when pulling 2643baf on daemonsy:patch-1 into bd1fb2c on JedWatson:master.

[JedWatson]

Thanks @daemonsy

[daemonsy]

Sure thing :)