[gnome-builder] Update CONTRIBUTING.md

[Alexandre Franke <afranke src gnome org>]

commit 2c097bc192050e31f9d7a527627d785ece25adc1
Author: Alexandre Franke <alexandre franke gmail com>
Date:   Sat Feb 17 22:13:14 2018 +0000

    Update CONTRIBUTING.md

 CONTRIBUTING.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index eb1e83c6c..05fef9be3 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -83,7 +83,7 @@ G_DECLARE_FINAL_TYPE (ExampleObject, example_object, EXAMPLE, OBJECT, GObject)
 
 Builder's default C mode matches our style guide.
 
-### Be explit about ownership transfers
+### Be explicit about ownership transfers
 
 Since `GLib 2.44`, we've had helpful macros and functions to be explit about ownership transfers.
 Please use them as it drastically saves time when tracking down memory leaks.