Transcript doc rewrite
Remove mention of transcripts to customize doc
Tweaking changes to remove some clutter
Update index to reflect captions page change
Remove transcripts doc page, redirect path to Captions doc.

A few months ago, we (sneakily) dropped transcript support for many accounts,
and instead switched them to captions only. This makes the existing transcripts
doc a bit confusing.

For now, this will remove the transcripts doc entirely. If lots of older
customers who have access to the transcript capabilities have lots of questions
in the future, we can bring it back.
Copy tweaks to captions doc
Index HTML update
Merge pull request #31 from wistia/jm-transcriptdocoverhaul

Transcript doc overhaul