Update the man pages and generated text copies for nethack and recover.
I haven't looked at the other four (dlb, makedefs, dgn_comp, lev_comp).
recover's page referred to INSURANCE as being conditional, which is no
longer the case. nethack's page was missing a bunch of files to be
found in the playground and also a couple of environment variables.
I haven't read through the text of the page to try to see whether other
updates are warranted.
The generated text is wider than the previous copy (one or two space
right margin instead of 5 or so). I just used 'make nethack.txt' and
'make recover.txt' so don't know why that changed. (The older, wider
margin looks better, so if anyone knows how to fix this, please do.
And there's got to be a better way to force a blank line inside a
table than my <space><tab> hack.)