doc/*.6: Use typographer's double quotes

...where available.

groff_man_style(7):

Notes
...
     • When and how should I use quotation marks?

       ... groff, Heirloom Doctools troff, neatroff, and mandoc support
       all of the special characters \[oq], \[cq], \[lq], \[rq], \[aq],
       and \[dq] described in subsection “Portability” above.  DWB, Plan
       9, and Solaris troffs do not.  Interpolating the strings \*(lq
       and \*(rq portably yields directional double quotation marks, if
       available, in all these formatters (though neatroff does not
       supply a man macro package), but they cannot reliably be used in
       macro arguments.

doc/makedefs.6

@@ -192,7 +192,7 @@ is known and defined, otherwise exit shell false (1).
 .BI \-\-grep\-define " symbol"
 Force the value of
 .I symbol
-to be "defined."
+to be \*(lqdefined.\*(rq
 .I Symbol
 must already be known to
 .BR makedefs .
@@ -200,7 +200,7 @@ must already be known to
 .BI \-\-grep\-undef " symbol"
 Force the definition of
 .I symbol
-to be "undefined."
+to be \*(lqundefined.\*(rq
 .I Symbol
 must already be known to
 .BR makedefs .

doc/nethack.6

@@ -194,7 +194,7 @@ to a string consisting of an @ character followed by the path and filename.
 The
 .B \-u
 .I player-name
-option supplies the answer to the question "Who are you?".
+option supplies the answer to the question \*(lqWho are you?\*(rq.
 It overrides any name from the options or configuration file, USER, LOGNAME,
 or getlogin(), which will otherwise be tried in order.
 If none of these provides a useful name, the player will be asked for one.
@@ -208,19 +208,19 @@ suffix can be used to specify the profession, race, alignment and/or gender
 of the character.
 The full syntax of a
 .I player-name
-including a suffix is "name\-ppp\-rrr\-aaa\-ggg".
-"ppp" are at least the first three letters
+including a suffix is \*(lqname\-ppp\-rrr\-aaa\-ggg\*(rq.
+\*(lqppp\*(rq are at least the first three letters
 of the profession (this can also be specified using a separate
 .B \-p
 .I profession
 option).
-"rrr" are at least the first three letters of the character's
+\*(lqrrr\*(rq are at least the first three letters of the character's
 race (this can also be specified using a separate
 .B \-r
 .I race
 option).
-"aaa" are at least the first three letters of the character's
-alignment, and "ggg" are at least the first three letters of the
+\*(lqaaa\*(rq are at least the first three letters of the character's
+alignment, and \*(lqggg\*(rq are at least the first three letters of the
 character's gender.
 Any of the parts of the suffix may be left out.
 .PP