Add mandoc-manpage for logname(1)

and mark it as finished in README.

README

@@ -39,7 +39,7 @@ The following tools are implemented ('*' == finished, '#' == UTF-8 support,
 =* link            yes                             none
 =* ln              yes                             none
 =* logger          yes                             none
-=  logname         yes                             none
+=* logname         yes                             none
 =  ls              no                              -C, -R, -q, -u
    md5sum          non-posix                       none
 =  mkdir           yes                             none

logname.1

@@ -1,8 +1,16 @@
-.TH LOGNAME 1 sbase\-VERSION
-.SH NAME
-logname \- return the user's login name
-.SH SYNOPSIS
-.B logname
-.SH DESCRIPTION
-.B logname
-prints the login name of the current user.
+.Dd January 26, 2015
+.Dt LOGNAME 1 sbase\-VERSION
+.Sh NAME
+.Nm logname
+.Nd show login name
+.Sh SYNOPSIS
+.Nm logname
+.Sh DESCRIPTION
+.Nm
+writes the login name of the current user to stdout.
+.Sh STANDARDS
+The
+.Nm
+utility is compliant with the
+.St -p1003.1-2008
+specification.