add link to explain tslint issue with sfc and props type

ts/components/session/PillDivider.tsx

@@ -3,6 +3,8 @@ import React from 'react';
 interface ReceivedProps {
   text: string;
 }
+
+// Needed because of https://github.com/microsoft/tslint-microsoft-contrib/issues/339
 type Props = ReceivedProps;
 
 export const PillDivider: React.SFC<Props> = props => {

ts/components/session/SessionHTMLRenderer.tsx

@@ -7,6 +7,7 @@ interface ReceivedProps {
   key?: any;
 }
 
+// Needed because of https://github.com/microsoft/tslint-microsoft-contrib/issues/339
 type Props = ReceivedProps;
 
 export const SessionHtmlRenderer: React.SFC<Props> = ({