Fix link in Timing Adjustable (#3944)

Fixes a broken link where the `href` had `http://https://` instead of
`https://`

Author: momdo

understanding/20/timing-adjustable.html

@@ -45,7 +45,7 @@ <h2>Intent of Timing Adjustable</h2>
 
       <p>It also includes content that is advancing or updating at a rate beyond the user's ability to read and/or understand it. In other words, animated, moving or scrolling content introduces a time limit on a users ability to read content.</p>
 
-      <p>This success criterion is generally not applicable when the content repeats or is synchronized with other content, so long as the information and data is adjustable or otherwise under the control of the end user.  Examples of time limits for which this success criterion is not applicable include scrolling text that repeats, captioning, and <a href="http://https://www.w3.org/WAI/tutorials/carousels/">carousels</a>.  These are situations which do include time limits, but the content is still available to the user because it has controls for accessing it, as specified in <a href="../../guidelines/sc/20/pause-stop-hide.html">2.2.2 Pause, Stop, Hide</a>.</p>
+      <p>This success criterion is generally not applicable when the content repeats or is synchronized with other content, so long as the information and data is adjustable or otherwise under the control of the end user.  Examples of time limits for which this success criterion is not applicable include scrolling text that repeats, captioning, and <a href="https://www.w3.org/WAI/tutorials/carousels/">carousels</a>.  These are situations which do include time limits, but the content is still available to the user because it has controls for accessing it, as specified in <a href="../../guidelines/sc/20/pause-stop-hide.html">2.2.2 Pause, Stop, Hide</a>.</p>
 
       <p>In some cases, however, it is not possible to change the time limit (for example, for an auction or other real-time event) and exceptions are therefore provided for those cases.</p>