Fix CRLF or mixed CRLF/LF line terminations in Markdown files

[musicinmybrain]

Most of this repository has UNIX-style (LF) line terminators, but a few files have CRLF (DOS/Windows-style) line terminators, and CHANGELOG.md has mixed line terminators.

$ find * -type f | xargs file | grep CRLF | tee -a .gitattributes
CHANGELOG.md:                                          Unicode text, UTF-8 text, with CRLF, LF line terminators
README.md:                                             Unicode text, UTF-8 text, with CRLF line terminators
tests/data/c.c:                                        C source, ASCII text, with CRLF line terminators
tests/data/example.umpl:                               Unicode text, UTF-8 text, with CRLF line terminators
tests/data/sql.sql:                                    ASCII text, with CRLF line terminators

I chose to only touch the markdown files, fixing up the line terminators with dos2unix. This PR doesn’t change the text and didn’t involve any manual editing.

You might choose to ask git to take care of converting line endings for you by adjusting .gitattributes.