doc that you can't use both data-ride and $().carousel() on the same carousel; fixes #13896

[skip sauce]

docs/_includes/js/carousel.html

@@ -132,7 +132,7 @@
 
   <h3>Via data attributes</h3>
   <p>Use data attributes to easily control the position of the carousel. <code>data-slide</code> accepts the keywords <code>prev</code> or <code>next</code>, which alters the slide position relative to its current position. Alternatively, use <code>data-slide-to</code> to pass a raw slide index to the carousel <code>data-slide-to="2"</code>, which shifts the slide position to a particular index beginning with <code>0</code>.</p>
-  <p>The <code>data-ride="carousel"</code> attribute is used to mark a carousel as animating starting at page load.</p>
+  <p>The <code>data-ride="carousel"</code> attribute is used to mark a carousel as animating starting at page load. <strong class="text-danger">It cannot be used in combination with (redundant and unnecessary) explicit JavaScript initialization of the same carousel.</strong></p>
 
   <h3>Via JavaScript</h3>
   <p>Call carousel manually with:</p>