Markdown writer: include needed whitespace after HTML figure.

We use HTML for a figure in markdown dialects that can't
represent it natively.

Closes #5121.

src/Text/Pandoc/Writers/Markdown.hs

@@ -463,7 +463,7 @@ blockToMarkdown' opts (Para [Image attr alt (src,'f':'i':'g':':':tit)])
   | isEnabled Ext_raw_html opts &&
     not (isEnabled Ext_link_attributes opts) &&
     attr /= nullAttr = -- use raw HTML
-    (text . T.unpack . T.strip) <$>
+    ((<> blankline) . text . T.unpack . T.strip) <$>
       writeHtml5String opts{ writerTemplate = Nothing }
         (Pandoc nullMeta [Para [Image attr alt (src,"fig:" ++ tit)]])
   | otherwise = blockToMarkdown opts (Para [Image attr alt (src,tit)])

test/command/5121.md

@@ -0,0 +1,13 @@
+```
+% pandoc -f markdown -t markdown_strict
+![My caption](./my-figure.jpg){width=500px}
+
+## Header 2
+^D
+<figure>
+<img src="./my-figure.jpg" alt="My caption" width="500" /><figcaption>My caption</figcaption>
+</figure>
+
+Header 2
+--------
+```