clarify support of select items (which is none) for input-prepend/append

docs/base-css.html

@@ -959,7 +959,7 @@ For example, <code>section</code> should be wrapped as inline.
   <p>Adding on top of existing browser controls, Bootstrap includes other useful form components.</p>
 
   <h3>Prepended and appended inputs</h3>
-  <p>Add text or buttons before or after any text-based input.</p>
+  <p>Add text or buttons before or after any text-based input. Do note that <code>select</code> elements are not supported here.</p>
 
   <h4>Default options</h4>
   <p>Wrap a <code>.add-on</code> and an <code>input</code> with one of two classes to prepend or append text to an input.</p>

docs/templates/pages/base-css.mustache

@@ -890,7 +890,7 @@
   <p>{{_i}}Adding on top of existing browser controls, Bootstrap includes other useful form components.{{/i}}</p>
 
   <h3>{{_i}}Prepended and appended inputs{{/i}}</h3>
-  <p>{{_i}}Add text or buttons before or after any text-based input.{{/i}}</p>
+  <p>{{_i}}Add text or buttons before or after any text-based input. Do note that <code>select</code> elements are not supported here.{{/i}}</p>
 
   <h4>{{_i}}Default options{{/i}}</h4>
   <p>{{_i}}Wrap a <code>.add-on</code> and an <code>input</code> with one of two classes to prepend or append text to an input.{{/i}}</p>