FederationRestrictions: add explanation box

app/soapbox/features/federation_restrictions/index.js

@@ -7,6 +7,7 @@ import Column from '../ui/components/column';
 import { createSelector } from 'reselect';
 import { Map as ImmutableMap, OrderedSet as ImmutableOrderedSet } from 'immutable';
 import RestrictedInstance from './components/restricted_instance';
+import Accordion from 'soapbox/features/ui/components/accordion';
 
 const getHosts = createSelector([
   state => state.getIn(['instance', 'pleroma', 'metadata', 'federation', 'mrf_simple'], ImmutableMap()),
@@ -19,6 +20,8 @@ const getHosts = createSelector([
 
 const messages = defineMessages({
   heading: { id: 'column.federation_restrictions', defaultMessage: 'Federation Restrictions' },
+  boxTitle: { id: 'federation_restrictions.explanation_box.title', defaultMessage: 'Instance-specific policies' },
+  boxMessage: { id: 'federation_restrictions.explanation_box.message', defaultMessage: 'Normally servers on the Fediverse can communicate freely. {siteTitle} has imposed restrictions on the following servers.' },
 });
 
 const mapStateToProps = state => ({
@@ -34,11 +37,31 @@ class FederationRestrictions extends ImmutablePureComponent {
     intl: PropTypes.object.isRequired,
   };
 
+  state = {
+    explanationBoxExpanded: true,
+  }
+
+  toggleExplanationBox = setting => {
+    this.setState({ explanationBoxExpanded: setting });
+  }
+
   render() {
-    const { intl, hosts } = this.props;
+    const { intl, hosts, siteTitle } = this.props;
+    const { explanationBoxExpanded } = this.state;
 
     return (
       <Column icon='gavel' heading={intl.formatMessage(messages.heading)} backBtnSlim>
+        <div className='explanation-box'>
+          <Accordion
+            headline={intl.formatMessage(messages.boxTitle)}
+            expanded={explanationBoxExpanded}
+            onToggle={this.toggleExplanationBox}
+          >
+            {intl.formatMessage(messages.boxMessage, { siteTitle })}
+          </Accordion>
+
+        </div>
+
         <div className='federation-restrictions'>
           {hosts.map(host => <RestrictedInstance key={host} host={host} />)}
         </div>