patch 8.0.1247: not easy to find Debian build info

Problem:    Not easy to find Debian build info.
Solution:   Add a badge in the README file. (Dominique Pelle)

Author: brammool

README.md

@@ -4,6 +4,7 @@
 [![Coverage Status](https://coveralls.io/repos/vim/vim/badge.svg?branch=master&service=github)](https://coveralls.io/github/vim/vim?branch=master)
 [![Appveyor Build status](https://ci.appveyor.com/api/projects/status/o2qht2kjm02sgghk?svg=true)](https://ci.appveyor.com/project/chrisbra/vim)
 [![Coverity Scan](https://scan.coverity.com/projects/241/badge.svg)](https://scan.coverity.com/projects/vim)
++[![Debian CI](https://badges.debian.net/badges/debian/testing/vim/version.svg)](https://buildd.debian.org/vim)[![Debian CI](https://badges.debian.net/badges/debian/testing/vim/version.svg)](https://buildd.debian.org/vim)
 
 
 ## What is Vim? ##

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1247,
 /**/
     1246,
 /**/