fix instructions speakers formatting text wrap around penta img

"This is what will be broadcast" move beneath image and begin on its own line.

Indent to show Image and sentence are part of parent "Validate your final video" checklist step.

Fixes FOSDEM#182

instructions/fosdem2021/speakers.md

@@ -12,8 +12,10 @@ Here's what you'll need to do to get your talk video in:
 - Your room manager will then review your talk.
 - Make sure your room ends up marked with state "done" at https://upload.video.fosdem.org/overview .
 - Validate your final video using the link at the bottom of https://penta.fosdem.org/submission/FOSDEM21/event/123456 .
-![penta submission Final Video URL](final_video_url.png)
-This is what will be broadcast at FOSDEM 2021. In case this looks good, no feedback is needed from you. In case of any issues, please contact [[email protected]](mailto:[email protected]) . Hints:
+
+  ![penta submission Final Video URL](final_video_url.png)
+
+  - This is what will be broadcast at FOSDEM 2021. In case this looks good, no feedback is needed from you. In case of any issues, please contact [[email protected]](mailto:[email protected]) . Hints:
   - Never share this link. Share your talk's unique event id.
   - Particularly check the end of the video. Make sure FOSDEM has the full recording.