Update and add `@btn-hover-color` to Customize page

customize.html

@@ -569,6 +569,9 @@ lead: Customize Bootstrap's components, LESS variables, and jQuery plugins to ge
           <input type="text" placeholder="@brand-info">
           <label>@btn-info-border</label>
           <input type="text" placeholder="@btn-info-bg">
+          <h4>Button hover</h4>
+          <label>@btn-hover-color</label>
+          <input type="text" placeholder="@btn-default-color">
         </div>
         <div class="col-lg-6">
           <h4>Success</h4>

less/variables.less

@@ -117,7 +117,7 @@
 @btn-info-bg:                    @brand-info;
 @btn-info-border:                @btn-info-bg;
 
-@btn-hover-color:                #fff;
+@btn-hover-color:                @btn-default-color;
 
 
 // Forms