Add mandoc-manpage for nice(1)

and mark it as finished in README.

README

@@ -46,7 +46,7 @@ The following tools are implemented ('*' == finished, '#' == UTF-8 support,
 =* mkfifo          yes                             none
 =  mktemp          non-posix                       none
 =* mv              yes                             (-i)
-=  nice            yes                             none
+=* nice            yes                             none
 =  nl              no                              -d, -f, -h, -l, -n, -p, -v, -w
 =  nohup           yes                             none
    paste           yes                             none

nice.1

@@ -1,18 +1,39 @@
-.TH NICE 1 sbase\-VERSION
-.SH NAME
-nice \- invoke a utility with an altered nice value
-.SH SYNOPSIS
-.B nice
-.RB [ \-n inc ]
-.I command
-.RI [ options ...]
-.SH DESCRIPTION
-.B nice
-invokes
-.IR command
-with a nice value equal to the current nice value plus
-.IR inc,
-which defaults to 10 if unspecified.
-
-.SH SEE ALSO
-.IR renice (1) nice (2)
+.Dd January 28, 2015
+.Dt NICE 1 sbase\-VERSION
+.Sh NAME
+.Nm nice
+.Nd run command with altered niceness
+.Sh SYNOPSIS
+.Nm nice
+.Op Fl n Ar inc
+.Ar cmd
+.Op Ar arg ...
+.Sh DESCRIPTION
+.Nm
+runs
+.Ar cmd
+with the current niceness plus
+.Ar inc .
+A negative niceness is reserved to the superuser.
+.Sh OPTIONS
+.Bl -tag -width Ds
+.It Fl n Ar inc
+Change niceness by
+.Ar inc ,
+ranging from
+.Sy -20
+(highest priority)
+to
+.Sy +20
+(lowest priority).
+Default is 10.
+.El
+.Sh SEE ALSO
+.Xr renice 2 ,
+.Xr nice 2
+.Sh STANDARDS
+The
+.Nm
+utility is compliant with the
+.St -p1003.1-2008
+specification.

nice.c

@@ -12,7 +12,7 @@
 static void
 usage(void)
 {
-	eprintf("usage: nice [-n inc] command [options ...]\n");
+	eprintf("usage: nice [-n inc] cmd [arg ...]\n");
 }
 
 int