[git-buildpackage] [PATCH] doc: expand --git-pbuilder-options docs

[Ken Dreyer]

Give an example of how to use the --git-pbuilder-options option, and
explain how it interacts with git-pbuilder.
---
 docs/manpages/gbp-buildpackage.sgml | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/docs/manpages/gbp-buildpackage.sgml b/docs/manpages/gbp-buildpackage.sgml
index 31faabc..f69f17a 100644
--- a/docs/manpages/gbp-buildpackage.sgml
+++ b/docs/manpages/gbp-buildpackage.sgml
@@ -417,7 +417,20 @@
             <para>
               Options to pass to pbuilder when building via &git-pbuilder; (either
               via <option>--git-pbuilder</option>, <option>--git-qemubuilder</option>
-              or the corresponding configuration file options).
+              or the corresponding configuration file options). It does so by
+              using the <envar>GIT_PBUILDER_OPTIONS</envar> environment
+              variable to pass options to &git-pbuilder;.
+            </para>
+            <para>
+	      As an example, to tell pbuilder to use an alternate .pbuilderrc
+              file, you may run &gbp-buildpackage; with
+              <option>--git-pbuilder-options="--configfile
+	      /tmp/my/pbuilderrc"</option>". See <command>man
+	      pbuilder</command> for more options to pass through here.
+            </para>
+            <para>
+              If unset the <envar>GIT_PBUILDER_OPTIONS</envar> environment
+              variable will be left untouched.
             </para>
           </listitem>
 	</varlistentry>
-- 
2.13.3