Fix setting class name for videos (#648)

Even though this looks like an HTML element, it's rendered by React so
apparently needs to be called `className`.

README.md

@@ -309,7 +309,7 @@ Videos are stored in the `public/videos` folder. You should use subfolders to or
 To add a video:
 
 ```markdown
-<video title="Write a description of the video here as 'alt text' for accessibility." class="max-w-auto h-auto" controls>
+<video title="Write a description of the video here as 'alt text' for accessibility." className="max-w-auto h-auto" controls>
     <source src="/videos/run/sessions/demo.mp4" type="video/mp4"></source>
 </video>
 ```

docs/run/sessions.mdx

@@ -29,7 +29,7 @@ The basic workflow for sessions is as follows:
 3. The _interactive timeout_ runs between the jobs in a session. Every session has an interactive timeout value (ITTL, or interactive time to live). If there are no session jobs queued within the ITTL window, the session is temporarily deactivated and normal job selection resumes. A deactivated session can be resumed for the next job<sup>*</sup> if the session has not reached its maximum timeout value.
 3. If the maximum timeout value is reached, the sessions end and any remaining queued jobs fail.
 
-<video title="A line of users is shown. The one in the current session becomes larger than the rest and has rotating arrows around them, indicating that they are the priority. Boxes (jobs) are seen being sent to the QPU (represented by a chandelier) from the current user. Other users begin to pop up during the animation and their jobs appear beneath them as they wait for the prioritized user's session to end. A progress bar appears above the prioritized user to represent the interactive TTL. After the prioritized user's session finishes, the line moves ahead toward the system, and the next person's jobs can begin processing." class="max-w-auto h-auto" controls>
+<video title="A line of users is shown. The one in the current session becomes larger than the rest and has rotating arrows around them, indicating that they are the priority. Boxes (jobs) are seen being sent to the QPU (represented by a chandelier) from the current user. Other users begin to pop up during the animation and their jobs appear beneath them as they wait for the prioritized user's session to end. A progress bar appears above the prioritized user to represent the interactive TTL. After the prioritized user's session finishes, the line moves ahead toward the system, and the next person's jobs can begin processing." className="max-w-auto h-auto" controls>
   <source src="/videos/run/sessions/demo.mp4" type="video/mp4"></source>
 </video>