revert doc changes

Author: gengliangwang

docs/configuration.md

@@ -1185,40 +1185,35 @@ Apart from these, the following properties are also available, and may be useful
   <td><code>spark.ui.reverseProxy</code></td>
   <td>false</td>
   <td>
-    Enable running Spark Master as reverse proxy for worker and application UIs. In this mode, 
-    the Spark master will reverse proxy the worker and application UIs to enable access without 
-    requiring direct access to their hosts. 
-    Use it with caution, as worker and application UI will not be accessible directly, you will 
-    only be able to access them through the spark master/proxy public URL. 
-    This setting affects all the workers and application UIs running in the cluster and must be 
-    set on all the workers, drivers and masters.  </td>
+    Enable running Spark Master as reverse proxy for worker and application UIs. In this mode, Spark master will reverse proxy the worker and application UIs to enable access without requiring direct access to their hosts. Use it with caution, as worker and application UI will not be accessible directly, you will only be able to access them through spark master/proxy public URL. This setting affects all the workers and application UIs running in the cluster and must be set on all the workers, drivers and masters.
+  </td>
   <td>2.1.0</td>
 </tr>
 <tr>
   <td><code>spark.ui.reverseProxyUrl</code></td>
   <td></td>
   <td>
-    If the Spark UI should be served through another front-end reverse proxy, this is the URL 
+    If the Spark UI should be served through another front-end reverse proxy, this is the URL
     for accessing the Spark master UI through that reverse proxy.
     This is useful when running proxy for authentication e.g. an OAuth proxy. The URL may contain
-    a path prefix, like <code>http://mydomain.com/path/to/spark/</code>, allowing you to serve the 
-    UI for multiple Spark clusters and other web applications through the same virtual host and 
+    a path prefix, like <code>http://mydomain.com/path/to/spark/</code>, allowing you to serve the
+    UI for multiple Spark clusters and other web applications through the same virtual host and
     port.
-    Normally, this should be an absolute URL including scheme (http/https), host and port. 
-    It is possible to specify a relative URL starting with "/" here. In this case, all URLs 
-    generated by the Spark UI and Spark REST APIs will be server-relative links -- this will still 
+    Normally, this should be an absolute URL including scheme (http/https), host and port.
+    It is possible to specify a relative URL starting with "/" here. In this case, all URLs
+    generated by the Spark UI and Spark REST APIs will be server-relative links -- this will still
     work, as the entire Spark UI is served through the same host and port.
-    <br/>The setting affects link generation in the Spark UI, but the front-end reverse proxy 
+    <br/>The setting affects link generation in the Spark UI, but the front-end reverse proxy
     is responsible for
     <ul>
       <li>stripping a path prefix before forwarding the request,</li>
       <li>rewriting redirects which point directly to the Spark master,</li>
-      <li>redirecting access from <code>http://mydomain.com/path/to/spark</code> to 
+      <li>redirecting access from <code>http://mydomain.com/path/to/spark</code> to
       <code>http://mydomain.com/path/to/spark/</code> (trailing slash after path prefix); otherwise
       relative links on the master page do not work correctly.</li>
     </ul>
-    This setting affects all the workers and application UIs running in the cluster and must be set 
-    identically on all the workers, drivers and masters. In is only effective when 
+    This setting affects all the workers and application UIs running in the cluster and must be set
+    identically on all the workers, drivers and masters. In is only effective when
     <code>spark.ui.reverseProxy</code> is turned on. This setting is not needed when the Spark
     master web UI is directly reachable.  </td>
   <td>2.1.0</td>