chore: RealtimeBoard -> Miro

closes #996

app/embeds/Miro.js

@@ -0,0 +1,26 @@
+// @flow
+import * as React from 'react';
+import Frame from './components/Frame';
+
+const URL_REGEX = /^https:\/\/(?:realtimeboard|miro).com\/app\/board\/(.*)$/;
+
+type Props = {
+  url: string,
+  matches: string[],
+};
+
+export default class RealtimeBoard extends React.Component<Props> {
+  static ENABLED = [URL_REGEX];
+
+  render() {
+    const { matches } = this.props;
+    const boardId = matches[1];
+
+    return (
+      <Frame
+        src={`https://realtimeboard.com/app/embed/${boardId}`}
+        title={`RealtimeBoard (${boardId})`}
+      />
+    );
+  }
+}