Rename config.doctype value "html_5" to "html5"
With config.doctype = html_5 you can render your Website as a HTML5 document. What hurts me every time when I use this is the underscore.
Please try the following:
Type: typo_3. Does it hurt? You know how I feel ;)
My suggestion is to change the option to html5, deprecate "html_5" and remove it in a later version.
(issue imported from #M17001)