[gxml] Fixed error message to enable DevHelp and GIR docs

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 8afb6142b4b3d0858354d91d807d4bf56e136a76
Author: Daniel Espinosa <esodan gmail com>
Date:   Tue Jun 16 13:36:34 2015 -0500

    Fixed error message to enable DevHelp and GIR docs

 configure.ac |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 2ebed63..3f707e6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -190,13 +190,13 @@ fi
 
 if test x$enable_devhelp_docs = xyes; then
   if test x$have_valadoc = xno -o x$have_gtkdoc = xno; then
-    AC_MSG_ERROR([valadoc and gtk-doc is required, to generate devhelp documentation. Use --enable-valadoc 
and --enable-gtk-doc])
+    AC_MSG_ERROR([valadoc and gtk-doc is required, to generate devhelp documentation. Use --enable-valadoc 
and --enable-gtk-docs])
   fi
 fi
 
 if test x$enable_gir_docs = xyes; then
   if test x$have_valadoc = xno; then
-    AC_MSG_ERROR([valadoc is required, to generate GIR documentation. Use --enable-valadoc and 
--enable-gtk-doc])
+    AC_MSG_ERROR([valadoc is required, to generate GIR documentation. Use --enable-valadoc and 
--enable-gtk-docs])
   fi
 fi