Rename documentation files for consistency

jumbo's current documentation files have inconsistent names. Some README* files use a dash (e.g., README-PDF) and others use a dot (e.g., README.BitLocker). I think we should standardize on dashes, keeping uses of dots reserved for filename suffixes indicating file type. Further, some are named very differently like CRAM-MD5.txt, DiskCryptor-HOWTO.md, NETNTLM_README - we should bring these to the same naming scheme (keeping the .md suffix where appropriate).

There's also the question on when to have a filename start with README, if ever. We currently don't do that for most things that are not per-format, and we do it for most things that are per-format. If that's indeed the distinction and if we want to keep it, then maybe some other word in place of README would be more appropriate (any suggestions?)

Now that we have several .md files, should we also start to use .txt suffixes (would be a change from core, but that's OK) or should we drop the few that we already have? Our current use of .txt is inconsistent, and that's probably wrong.

Start by listing the documentation files named in the issue, including README-PDF, README.BitLocker, CRAM-MD5.txt, DiskCryptor-HOWTO.md, and NETNTLM_README, then compare their naming and suffix patterns. Done means agreeing on the README convention, dash usage, and .md/.txt policy, and applying that scheme consistently across the affected files.