[changed] Add deprecation warning that factories will be removed

For details see react-bootstrap#825

Author: mtscout6

src/templates/factory.index.js.template

@@ -2,6 +2,8 @@
 import <%= component %> from './<%= component %>';
 <% }); %>
 
+console.warn('Support for factories will be removed in v0.25, for details see https://github.com/react-bootstrap/react-bootstrap/issues/825');
+
 export default {
 <% _.forEach(components, function (component) { %>
   <%= component %>,

src/templates/factory.js.template

@@ -1,4 +1,6 @@
 import React from 'react';
 import <%= name %> from '../<%= name %>';
 
+console.warn('Support for factories will be removed in v0.25, for details see https://github.com/react-bootstrap/react-bootstrap/issues/825');
+
 export default React.createFactory(<%= name %>);