[gitg] Fix build instructions

[Alberto Fanjul <albfan src gnome org>]

commit 56806922526aed95f00154de4c156dc6994dfb9c
Author: Alberto Fanjul <albertofanjul gmail com>
Date:   Sun May 19 22:46:45 2019 +0200

    Fix build instructions
    
    Remove old reference to INSTALL document

 README.md | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
---
diff --git a/README.md b/README.md
index 5369e690..e7fb6904 100644
--- a/README.md
+++ b/README.md
@@ -20,11 +20,9 @@ $ tar Jxf gitg-3.30.1.tar.xz
 $ cd gitg-3.30.1
 $ meson --prefix=/usr build
 $ ninja -C build
-$ sudo ninja -C install
+$ sudo ninja -C build install
 ```
 
-For more information on installing gitg, please see INSTALL.
-
 ## Building gitg from git
 
 The gitg repository is hosted on git.gnome.org. To build from git: