[gnome-software] trivial: Fix up .gitignore to have a clean checkout

[Richard Hughes <rhughes src gnome org>]

commit 79082601e6dedc2ddb1b113d1a3f409d144fea96
Author: Richard Hughes <richard hughsie com>
Date:   Mon May 23 15:22:21 2016 +0100

    trivial: Fix up .gitignore to have a clean checkout

 Makefile.am |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 63e78c0..ee4948d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -25,6 +25,7 @@ MAINTAINERCLEANFILES =                                        \
        config.sub                                      \
        configure                                       \
        depcomp                                         \
+       gtk-doc.make                                    \
        install-sh                                      \
        ltmain.sh                                       \
        Makefile.in                                     \