[FLAC 1.5.0] man page generation produces HYPHEN instead of HYPHEN-MINUS

[vyncere]

This issue has been discovered during the investigation of the issue #861.

Man pages generated from markdown sources, contains HYPHEN (text hyphen) characters instead of HYPHEN-MINUS characters (plain text minus).

Consequently, the syntax of the options, such as -v (--version) are wrong. The current man pages of flac and metaflac are misleading : copy and paste the option(s) in the terminal create a syntactically wrong call of the command.

[H2Swine]

Should use \-a or ticks around -a?

flac.md has a draft in the works. Don't know what workflow devs find useful, but I could fix this too.