Add a note to the .rich-text styles about email_markdown.py
Add a note to the .rich-text styles about email_markdown.py

I meant to add this to my previous change which added markdown rendering for
HTML, but I forgot to commit it before pushing, so it just sat in my working
dir. Trivial change.

reviewboard/reviewboard,beol/reviewboard,chipx86/reviewboard,sgallagher/reviewboard,1tush/reviewboard,davidt/reviewboard,davidt/reviewboard,bkochendorfer/reviewboard,bkochendorfer/reviewboard,KnowNo/reviewboard,custode/reviewboard,reviewboard/reviewboard,brennie/reviewboard,beol/reviewboard,chipx86/reviewboard,1tush/reviewboard,1tush/reviewboard,reviewboard/reviewboard,bkochendorfer/reviewboard,sgallagher/reviewboard,1tush/reviewboard,KnowNo/reviewboard,KnowNo/reviewboard,davidt/reviewboard,beol/reviewboard,1tush/reviewboard,sgallagher/reviewboard,custode/reviewboard,beol/reviewboard,bkochendorfer/reviewboard,davidt/reviewboard,brennie/reviewboard,1tush/reviewboard,1tush/reviewboard,1tush/reviewboard,brennie/reviewboard,KnowNo/reviewboard,reviewboard/reviewboard,custode/reviewboard,chipx86/reviewboard,brennie/reviewboard,sgallagher/reviewboard,chipx86/reviewboard,1tush/reviewboard,custode/reviewboard