[docs] Fix IE 11 support

Related to markedjs/marked#1585 (comment)

Author: oliviertassinari

docs/src/modules/components/AppTableOfContents.js

@@ -1,7 +1,7 @@
 /* eslint-disable react/no-danger */
 import React from 'react';
 import PropTypes from 'prop-types';
-import marked from 'marked';
+import marked from 'marked/lib/marked';
 import throttle from 'lodash/throttle';
 import clsx from 'clsx';
 import Box from '@material-ui/core/Box';

docs/src/modules/components/MarkdownElement.js

@@ -2,7 +2,7 @@ import React from 'react';
 import PropTypes from 'prop-types';
 import clsx from 'clsx';
 import { useSelector } from 'react-redux';
-import marked from 'marked';
+import marked from 'marked/lib/marked';
 import { withStyles } from '@material-ui/core/styles';
 import textToHash from 'docs/src/modules/utils/textToHash';
 import prism from 'docs/src/modules/components/prism';