[retro-gtk] readme: Fix a grammatical error

[Adrien Plazas <aplazas src gnome org>]

commit 9e590d6da4addbf3089166122a9dbf4e68a2062d
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Sun Nov 15 15:29:51 2020 +0100

    readme: Fix a grammatical error

 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/README.md b/README.md
index b61cb3c4..0d9e5f21 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ The GTK Libretro frontend framework.
 video game console emulators, video games and similar multimedia software. Such
 plugins are called Libretro cores.
 
-RetroGTK is a framework easing the usage of Libretro cores in conjunction with
+RetroGTK is a framework easing the use of Libretro cores in conjunction with
 [GTK](https://www.gtk.org/).
 
 It encourages the cores to be installed in a well defined centralized place —