Add mandoc-manpage for mv(1)

and mark it as finished in README.
Make it clear that -i has not been implemented yet and drop the
flag in the code instead of erroring out.

mv.1

@@ -1,22 +1,36 @@
-.TH MV 1 sbase\-VERSION
-.SH NAME
-mv \- move files and directories
-.SH SYNOPSIS
-.B mv
-.RB [ \-f ]
-.I file
-.RI [ name ]
-.P
-.B mv
-.RB [ \-f ]
-.RI [ file ...]
-.RI [ directory ]
-.SH DESCRIPTION
-.B mv
-moves or renames a given file or directory, naming it the given name.  If
-multiple files and directories are listed they will be moved into the given
-directory.
-.SH OPTIONS
-.TP
-.B \-f
-do not prompt for confirmation before overwriting the destination path.
+.Dd January 28, 2015
+.Dt MV 1 sbase\-VERSION
+.Sh NAME
+.Nm mv
+.Nd move files and directories
+.Sh SYNOPSIS
+.Nm mv
+.Op Fl f | Fl i
+.Ar source ...
+.Ar destination
+.Sh DESCRIPTION
+.Nm
+moves each
+.Ar source
+to
+.Ar destination .
+If only one
+.Ar source
+is given and
+.Ar destination
+is not a directory,
+.Nm
+overwrites the latter with the former.
+.Sh OPTIONS
+.Bl -tag -width Ds
+.It Fl f | Fl i
+Do not prompt | Prompt before overwriting
+.Ar destination .
+Prompting has not been implemented yet.
+.El
+.Sh STANDARDS
+The
+.Nm
+utility is compliant with the
+.St -p1003.1-2008
+specification except from prompting.