[Search] Make the feature name link to a learn more screen in the first-run experience.

chrome/browser/resources/contextual_search/promo.css

 /* Copyright 2014 The Chromium Authors. All rights reserved.
    Use of this source code is governed by a BSD-style license that can be
    found in the LICENSE file.
 */
 @font-face {
   font-family: 'Roboto2';
   font-weight: 400;
   src: local('Roboto'), local('Roboto2-Regular'),
       url(/roboto.woff2) format('woff2'), url(/roboto.woff) format('woff');
 }
 
 body {
   color: #414141;
   font-family: 'Roboto2', sans-serif;
   margin: 0;
 }
 
 a {
   color: #414141;
+  text-decoration: none;
 }
 
 .colored {
   color: rgb(66, 133, 244);
 }
 
 .label {
   display: inline-block;
   font-size: 14px;
   font-weight: bold;
   padding: 28px;
   white-space: nowrap;
 }
 
 .label a {
-  text-decoration: none;
   text-transform: uppercase;
 }
 
 #button-container {
   text-align: right;
   width: 100%;
 }
 
 #container.hide {
   -webkit-transform: scale(0.95);
   -webkit-transition-duration: 218ms;
   -webkit-transition-property: opacity, -webkit-transform;
   opacity: 0;
 }
 
 #description {
   font-size: 16px;
   line-height: 1.4em;
   margin: 32px 16px 4px 16px;
 }
 
 #heading {
   font-size: 24px;
   letter-spacing: 1px;
   margin-top: 0;
   text-align: center;
 }