[ghex] README.md: fix headings

[Logan Rathbone <larathbone src gnome org>]

commit aa54a2685f2e712ca4165c13cdbb4c0a6a9250c7
Author: Logan Rathbone <poprocks gmail com>
Date:   Thu Aug 12 18:45:26 2021 -0400

    README.md: fix headings

 README.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/README.md b/README.md
index b7628f67..2dee91aa 100644
--- a/README.md
+++ b/README.md
@@ -11,11 +11,11 @@ other. GHex is a useful tool for working with raw data.
 
 Please see the meson.build file for details.
 
-# Use
+## Use
 
 Please refer to the help files.
 
-# Authors and Copyright Information
+## Authors and Copyright Information
 
 The original author of GHex was Jaka Mocnik, who licensed it under the
 GPLv2+. Please see the COPYING file for a full copy of the licence.