doc/*.[67]: Drop redundant calls and requests

Sectioning and paragraphing macros always break the output line.

(Sub)sectioning macros always set text after the heading as a paragraph.

Fixes:

$ mandoc -T lint doc/*.[67] # output edited
doc/makedefs.6:49:2: WARNING: skipping paragraph macro: PP after SH
doc/nethack.6:367:2: WARNING: skipping paragraph macro: br after PP
doc/nethack.6:365:2: WARNING: skipping paragraph macro: PP empty
doc/nethack.6:157:2: WARNING: skipping paragraph macro: PP after SH
doc/nethack.6:431:2: WARNING: skipping paragraph macro: PP after SH
doc/nethack.6:673:2: WARNING: skipping paragraph macro: PP after SH
doc/nethack.6:676:2: WARNING: skipping paragraph macro: PP after SH
doc/recover.6:29:2: WARNING: skipping paragraph macro: PP after SH
doc/recover.6:125:2: WARNING: skipping paragraph macro: PP after SH
doc/recover.6:141:2: WARNING: skipping paragraph macro: PP after SH
doc/mnh.7:23:2: WARNING: skipping paragraph macro: PP after SH
doc/mnh.7:46:2: WARNING: skipping paragraph macro: PP after SH

doc/recover.6

@@ -26,7 +26,6 @@ recover \- recover a NetHack game interrupted by disaster
 ]
 .I "base1 base2" ...
 .SH DESCRIPTION
-.PP
 Occasionally, a NetHack game will be interrupted by disaster
 when the game or the system crashes.
 Prior to NetHack v3.1, these games were lost because various information
@@ -122,7 +121,6 @@ In either case,
 .I recover
 is easily compiled from the distribution utility directory.
 .SH NOTES
-.PP
 Like
 .I nethack
 itself,
@@ -138,7 +136,6 @@ will find them in the uncompressed form.
 .SH "SEE ALSO"
 nethack(6)
 .SH BUGS
-.PP
 .I recover
 makes no attempt to find out if a base name specifies a game in progress.
 If multiple machines share a playground, this would be impossible to