dpkg-parsechangelog(1): Document --file and --label parser options

These options have been supported for a very long time, and --label has
been used up to very recently by dpkg-parsechangelog, just document them
to make it clear that these need to be supported by the parsers.

debian/changelog

@@ -120,6 +120,7 @@ dpkg (1.17.0) UNRELEASED; urgency=low
     Thanks to Bernhard R. Link <brlink@debian.org>.
   * Add support for mipsn32(el) and mips64(el) to arch tables.
     Thanks to YunQiang Su <wzssyqa@gmail.com>. Closes: #685096, #707323
+  * Document --file and --label parser options in dpkg-parsechangelog(1).
 
   [ Updated programs translations ]
   * Fix typo in Spanish translation of update-alternatives.

man/dpkg-parsechangelog.1

@@ -19,7 +19,7 @@
 .\" You should have received a copy of the GNU General Public License
 .\" along with this program.  If not, see <http://www.gnu.org/licenses/>.
 .
-.TH dpkg\-parsechangelog 1 "2013-04-02" "Debian Project" "dpkg utilities"
+.TH dpkg\-parsechangelog 1 "2013-07-06" "Debian Project" "dpkg utilities"
 .SH NAME
 dpkg\-parsechangelog \- parse Debian changelog files
 .
@@ -69,6 +69,13 @@ the changelog parser, e.g. the range of entries or the format
 of the output. They need to be supported by the parser script
 in question. See also \fBNOTES\fP.
 .TP
+.BI \-\-file " file"
+Set the changelog filename to parse. Default is '-' (standard input).
+.TP
+.BR \-l ", " \-\-label " \fIfile\fP"
+Set the name of the changelog file to use in error messages, instead
+of using the name from the \fB\-\-file\fP option, or its default value.
+.TP
 .BI \-\-format " output-format"
 Set the output format. Currently supported values are
 .IR dpkg " and " rfc822 .