Flesh out the IMAP section in usingcurl/reademail.md

[ernstki]

There wasn't a lot to go on here, nor in the man page, so I took it upon myself to add a few more examples to the IMAP part of usingcurl/reademail.md. Mostly so I could have something to refer back to later, since this IMAP stuff didn't stick very well in my brain the first couple times.

This IMAP cheatsheet helped me out a lot, and I'd be happy to add another commit to add that as a reference, if desired.

[ernstki]

These lines represent output from a command. Not sure I would want it wrapped just to appease check-quotes.pl, but if this is a hard choice (e.g. because it makes the PDF look bad, or we don't want to alter the CI routines around this), I'll just ellipsize it until it fits.

[ernstki]

• (t)oo wide quoted line, please wrap
  • this is literal output from a command; not sure what you want to do about that — ellipsize it?
  • ref: check-quotes.pl at line 33
  • I will push a commit to fix the "woo" typo, though
• More than 30 ppm of exclamations
  • basically this says "never use an exclamation point," I think; I'll remove it if this is what is desired, or if not, I'll fix the linter settings to allow it
• Spelling check failed
  • not sure how to spell 57th or 57^th and appease the spell checker; I doubt using a Unicode ordinal will turn out better