Add react-redux.js.org

Currently working on setting up docs publishing for React-Redux, per https://github.com/reduxjs/react-redux/issues/1031 .

Site is hosted at https://react-redux-docs.netlify.com/ .  Semi-placeholder content for now (just the one page).  We'll start publishing things for real as soon as we can figure out which site gen tool we're using.

CNAME has been added at https://github.com/reduxjs/react-redux/blob/master/CNAME , and we're good with the terms and conditions.

cnames_active.js

@@ -1094,6 +1094,7 @@ var cnames_active = {
   "react-native-floating-labels": "mayank-patel.github.io/react-native-floating-labels",
   "react-observatory": "hosting.gitbook.com",
   "react-pivottable": "plotly.github.io/react-pivottable",
+  "react-redux": "react-redux-docs.netlify.com"
   "react-responsive-carousel": "leandrowd.github.io/react-responsive-carousel", // noCF? (don´t add this in a new PR)
   "react-shared": "rvikmanis.github.io/react-shared", // noCF? (don´t add this in a new PR)
   "react-state": "tannerlinsley.github.io/react-state",