Remove .dl-horizontal; it's redundant to the grid system; fixes #18652

[skip sauce]

docs/content/typography.md

@@ -215,12 +215,12 @@ Place all list items on a single line with `display: inline-block;` and some bas
 </ul>
 {% endexample %}
 
-### Horizontal description
+### Description list alignment
 
 Align terms and descriptions horizontally by using our grid system's predefined classes (or semantic mixins). For longer terms, you can optionally add a `.text-truncate` class to truncate the text with an ellipsis.
 
 {% example html %}
-<dl class="dl-horizontal">
+<dl class="row">
   <dt class="col-sm-3">Description lists</dt>
   <dd class="col-sm-9">A description list is perfect for defining terms.</dd>
 

docs/migration.md

@@ -54,7 +54,7 @@ New to Bootstrap 4 is the Reboot, a new stylesheet that builds on Normalize with
 
 - Moved all `.text-` utilities to the `_utilities.scss` file.
 - Dropped the `.page-header` class entirely.
-- `.dl-horizontal` now requires grid classes, increasing flexbility in column widths.
+- `.dl-horizontal` has been dropped. Instead, use `.row` on `<dl>` and use grid column classes on its `<dt>` and `<dd>` children.
 - Custom `<blockquote>` styling has moved to classes—`.blockquote` and the `.blockquote-reverse` modifier.
 
 ### Images

scss/_type.scss

@@ -101,13 +101,6 @@ mark,
   }
 }
 
-// Horizontal description lists w/ grid classes
-.dl-horizontal {
-  margin-right: -$grid-gutter-width;
-  margin-left: -$grid-gutter-width;
-  @include clearfix;
-}
-
 
 //
 // Misc