Add Bitcoin Transcripts section

[michaelfolkson]

I have put placeholders where I think the section should refer back to previous newsletters but I haven't actually set up those links. Still figuring out how you do those. If you could let me know I'll make sure the links actually work in future months :)

[harding]

To create links to specific parts of previous newsletters, we usually just click the hyperlink-blue bullet next to the specific item. E.g.:

That will give you the anchor link. Just turn it from an absolute URL (https://bitcoinops.org/foo/bar) into a relative URL (/foo/bar) so that it works correctly in localhost previews and gets checked by our internal link checker.

You don't need to worry about that for this month, I'll turn your placeholders into links for this PR.

I gave the content a quick skim and it LGTM, thanks! I'll edit it shortly and merge it into the main PR.

[harding]

Merged into the main PR with minimal content edits (just formatting). Great section this month, thanks Michael!