[gnome-mines] Add user manual to the list on the README and use markdown formatting for the button

[Robert Roth <robertroth src gnome org>]

commit 96e3520ac41ee2ab190d4f432db553e6545d7c7d
Author: Roger <sachanroger gmail com>
Date:   Mon Sep 2 19:36:28 2019 +0000

    Add user manual to the list on the README and use markdown formatting for the button

 README.md | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
---
diff --git a/README.md b/README.md
index 8347247..f9d8386 100644
--- a/README.md
+++ b/README.md
@@ -2,14 +2,12 @@
 
 Mines (previously gnomine) is a puzzle game where you locate mines floating in an ocean using only your 
brain and a little bit of luck.
 
-<a href='https://flathub.org/apps/details/org.gnome.Mines'><img width='240' alt='Download on Flathub' 
src='https://flathub.org/assets/badges/flathub-badge-i-en.png'/></a>
+[![Download on 
Flathub](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Flathub-badge-en.svg/240px-Flathub-badge-en.svg.png)](https://flathub.org/apps/details/org.gnome.Mines)
 
 ## Useful links
 
 - Homepage: <https://wiki.gnome.org/Apps/Mines>
-
+- User manual: <https://help.gnome.org/users/gnome-mines/stable/>
 - Report issues: <https://gitlab.gnome.org/GNOME/gnome-mines/issues/>
-
 - Donate: <https://www.gnome.org/friends/>
-
 - Translate: <https://wiki.gnome.org/TranslationProject>