Fix gnt-job info entry in gnt-job(8)

It currently reports "cancel" in its syntax, which is obviously a
cut&paste error.

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

man/gnt-job.sgml

@@ -107,7 +107,7 @@
     <refsect2>
       <title>INFO</title>
       <cmdsynopsis>
-        <command>cancel</command>
+        <command>info</command>
         <arg choice="req" rep="repeat"><replaceable>id</replaceable></arg>
       </cmdsynopsis>