Adds documention for the newline requirement before and after lists.

Change-Id: Id4357d86f8410d981df262d90bf7bcbeb165a056

Documentation/markdown.md

diff --git a/Documentation/markdown.md b/Documentation/markdown.md
index 22ed389..05fe794 100644
--- a/Documentation/markdown.md
+++ b/Documentation/markdown.md
@@ -102,6 +102,8 @@
 
 The second level items (above Orange, Pear) must be indented with more
 spaces than the item they are nested under. Above 2 spaces were used.
+Additionally, the entire list must be preceded and followed by a blank
+line.
 
 A numbered list: