remove lingering references to Less in the docs

docs/getting-started/third-party-support.md

@@ -16,7 +16,7 @@ Depending on the context, you may override as-needed (Option 1) or reset the box
  *
  * Reset individual elements or override regions to avoid conflicts due to
  * global box model settings of Bootstrap. Two options, individual overrides and
- * region resets, are available as plain CSS and uncompiled Less formats.
+ * region resets, are available as plain CSS and uncompiled Sass formats.
  */
 
 /* Option 1A: Override a single element's box model via CSS */
@@ -26,7 +26,7 @@ Depending on the context, you may override as-needed (Option 1) or reset the box
           box-sizing: content-box;
 }
 
-/* Option 1B: Override a single element's box model by using a Bootstrap Less mixin */
+/* Option 1B: Override a single element's box model by using a Bootstrap Sass mixin */
 .element {
   .box-sizing(content-box);
 }
@@ -41,7 +41,7 @@ Depending on the context, you may override as-needed (Option 1) or reset the box
           box-sizing: content-box;
 }
 
-/* Option 2B: Reset an entire region with a custom Less mixin */
+/* Option 2B: Reset an entire region with a custom Sass mixin */
 .reset-box-sizing {
   &,
   *,

docs/index.html

@@ -25,9 +25,9 @@ title: Bootstrap · The world's most popular mobile-first and responsive f
 
     <div class="row">
       <div class="col-sm-4">
-        <img src="assets/img/sass-less.png" alt="Sass and Less support" class="img-responsive">
+        <img src="assets/img/sass-less.png" alt="Sass support" class="img-responsive">
         <h3>Preprocessors</h3>
-        <p>Bootstrap ships with vanilla CSS, but its source code utilizes the two most popular CSS preprocessors, <a href="../css/#less">Less</a> and <a href="../css/#sass">Sass</a>. Quickly get started with precompiled CSS or build on the source.</p>
+        <p>Bootstrap ships with vanilla CSS, but its source code utilizes <a href="../css/#sass">Sass</a>, a popular CSS preprocessor. Quickly get started with precompiled CSS or build on the source.</p>
       </div>
       <div class="col-sm-4">
         <img src="assets/img/devices.png" alt="Responsive across devices" class="img-responsive">