[gjs: 1/2] Update README.md

[Philip Chimento <pchimento src gnome org>]

commit 72d0c2778585513b30c7f0634a48866c746ef3ae
Author: Nauman Umer <nmanumr gmail com>
Date:   Tue Apr 2 14:28:19 2019 +0000

    Update README.md

 README.md | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/README.md b/README.md
index 4f3ae39b..e21ef389 100644
--- a/README.md
+++ b/README.md
@@ -36,6 +36,8 @@ Hit Ctrl+D to exit.
 There are also facilities for generating code coverage reports.
 Type `gjs --help` for more information.
 
+`-d` only available in gjs >= 1.53.90
+
 ## Contributing
 
 For instructions on how to get started contributing to GJS, please read