DevTools: NetworkPanel: show link where resource timing is explained.

Source/devtools/front_end/components/helpScreen.css

 .help-window-outer {
     position: absolute !important;
     top: 0;
     left: 0;
     right: 0;
     bottom: 0;
     z-index: 2000;
 }
 
 .help-window-main {
     color: white;
     background-color: rgba(17, 17, 17, 0.85);
     display: -webkit-flex;
     -webkit-flex-direction: column;
     border-top-width: 0;
     border-radius: 10px;
 }
 
-.help-window-main a {
-    color: rgb(17, 85, 204);
-}
-
 .help-window-caption {
     border-bottom: solid 1px rgb(153, 153, 153);
     margin: 0 8px;
     padding: 0 2px;
     line-height: 28px;
 }
 
 .help-window-title {
     font-size: 16px;
     margin: 0;
@@ skipping 605 matching lines @@
 .settings-experiment-hidden {
     display: none;
 }
 
 .settings-experiment-hidden label {
     background-color: #ddd;
 }
 
 .settings-developer-mode .settings-experiment-hidden {
     display: block;
-}
+}