[gedit] build: take new README into consideration

[Jeremy Bicha <jbicha src gnome org>]

commit f2d75d13efcb7243f8efcf23a2cfd8325c74470c
Author: Alexandre Franke <alexandre franke gmail com>
Date:   Mon Dec 3 13:57:44 2018 +0100

    build: take new README into consideration
    
    autotools assume `README` but we renamed to `README.md`

 Makefile.am | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/Makefile.am b/Makefile.am
index 294eb4f70..901c91494 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -10,6 +10,7 @@ endif
 EXTRA_DIST =                   \
        HACKING                 \
        MAINTAINERS             \
+       README.md               \
        gedit.doap
 
 DISTCLEANFILES =               \