Changes to mflag.1

[larryhynes]

• given -> specified
• stdin -> 'the standard input'
• Delete superfluous 'the'
• Make 'cur' link clear

[larryhynes]

I'm a bit unclear on why -x includes the bit about '(Remember to use upper-case characters.)' - and -X doesn't, for instance.

[leahneukirchen]

I guess because -f -p would be -x FP for example.