Add bug for xmlns

diff --git a/doc/bugs/XHTML_needs_xmlns_attribute_on_html_element.mdwn b/doc/bugs/XHTML_needs_xmlns_attribute_on_html_element.mdwn
new file mode 100644 (file)
index 0000000..8bb8e1b
--- /dev/null
+++ b/doc/bugs/XHTML_needs_xmlns_attribute_on_html_element.mdwn
@@ -0,0 +1,3 @@
+XHTML needs `xmlns="http://www.w3.org/1999/xhtml"` on the `html` element;
+otherwise, it will not validate.
+--[[JoshTriplett]]