[gtkmm-documentation] Add examples/book/buildapp/.gitignore

[Kjell Ahlstedt <kjellahl src gnome org>]

commit d2d2f3b9c5ecf3b20faa00ad2f41b4a6efb289b5
Author: Kjell Ahlstedt <kjell ahlstedt bredband net>
Date:   Mon Oct 10 09:41:00 2016 +0200

    Add examples/book/buildapp/.gitignore
    
    Should have been included in the previous commit.

 examples/book/buildapp/.gitignore |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/examples/book/buildapp/.gitignore b/examples/book/buildapp/.gitignore
new file mode 100644
index 0000000..3119019
--- /dev/null
+++ b/examples/book/buildapp/.gitignore
@@ -0,0 +1,2 @@
+exampleapp
+resources.c