[json-glib] build: Fix syntax error in --enable-man define

[Emmanuele Bassi <ebassi src gnome org>]

commit 7ab837c98a10cc1464318e4e4d04426b6fcc070b
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Mon Dec 2 10:40:43 2013 +0000

    build: Fix syntax error in --enable-man define
    
    A missing comma was triggering a bad substitution and a warning when
    running the configure script.

 configure.ac |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 570f570..3e464be 100644
--- a/configure.ac
+++ b/configure.ac
@@ -265,8 +265,8 @@ dnl === Documentation =========================================================
 
 GTK_DOC_CHECK([1.13], [--flavour no-tmpl])
 
-AC_ARG_ENABLE([man,]
-              [AS_HELP_STRING([--enable-man], [generate man pages [default=auto]])],
+AC_ARG_ENABLE([man,],
+              [AS_HELP_STRING([--enable-man], [generate man pages @<:@default=auto@:>@])],
               [],
               [enable_man=maybe])