patch 7.4.846
Problem:    Some GitHub users don't know how to use issues.
Solution:   Add a file that explains the basics of contributing.
diff --git a/Filelist b/Filelist
index 1dc7fd0..166e2f4 100644
--- a/Filelist
+++ b/Filelist
@@ -482,6 +482,7 @@
 RT_ALL =	\
 		README.txt \
 		README.md \
+		CONTRIBUTING.md \
 		runtime/bugreport.vim \
 		runtime/doc/*.awk \
 		runtime/doc/*.pl \