AsciiDoc writer: add blank line after Div.

Closes #6308.

src/Text/Pandoc/Writers/AsciiDoc.hs

@@ -299,7 +299,7 @@ blockToAsciiDoc opts (Div (ident,classes,_) bs) = do
                       chomp admonitionBody $$
                       "===="
          _ -> blockListToAsciiDoc opts bs
-  return $ identifier $$ contents
+  return $ identifier $$ contents $$ blankline
 
 -- | Convert bullet list item (list of blocks) to asciidoc.
 bulletListItemToAsciiDoc :: PandocMonad m

test/command/6308.md

@@ -0,0 +1,18 @@
+```
+% pandoc -f org -t asciidoc
+* Header
+#+begin_tip
+I'm a tip
+#+end_tip
+
+** Subheader
+^D
+== Header
+
+[TIP]
+====
+I'm a tip
+====
+
+=== Subheader
+```