[gnome-chess] Fix flathub link and add link to user manual

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 12a502eb22440be7302a79dadb418b06db0ea51f
Author: Roger <sachanroger gmail com>
Date:   Tue Aug 27 21:08:22 2019 +0000

    Fix flathub link and add link to user manual

 README.md | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
---
diff --git a/README.md b/README.md
index 620d102..14a0c65 100644
--- a/README.md
+++ b/README.md
@@ -3,14 +3,12 @@
 GNOME Chess is a 2D chess game, where games can be played between a combination of human and computer 
players.
 GNOME Chess detects known third party chess engines for computer players.
 
-<a href='https://flathub.org/apps/details/org.gnome.chess'><img width='240' alt='Download on Flathub' 
src='https://flathub.org/assets/badges/flathub-badge-i-en.png'/></a>
+<a href='https://flathub.org/apps/details/org.gnome.Chess'><img width='240' alt='Download on Flathub' 
src='https://flathub.org/assets/badges/flathub-badge-i-en.png'/></a>
 
 ## Useful links
 
 - Homepage: <https://wiki.gnome.org/Apps/Chess>
-
+- User manual: <https://help.gnome.org/users/gnome-chess/stable/>
 - Report issues: <https://gitlab.gnome.org/GNOME/gnome-chess/issues/>
-
 - Donate: <https://www.gnome.org/friends/>
-
 - Translate: <https://wiki.gnome.org/TranslationProject>
\ No newline at end of file