fix: remove runtime warning by replacing UIManager.RCTVideo with UIManager.getViewManagerConfig('RCTVideo') (and ensuring backwards compat) (#1487)

* replaced UIManager.RCTVideo >  UIManager.getViewManagerConfig('RCTVideo')

* added requested changes

* updated changelog.md

* docs: adjust wording

.eslintrc

@@ -1,4 +1,4 @@
 {
   "extends": "airbnb",
   "parser": "babel-eslint"
-}
+}