html.lang: Remove unallowed whitespace
- In start tags, there cannot be whitespace between the less-than and the tag name
- In end tags, there cannot be whitespace between the less-than, slash, and the tag name
- Comments must end with "-->" (no space allowed between "--" and ">")
https://html.spec.whatwg.org/multipage/syntax.html#start-tags
https://html.spec.whatwg.org/multipage/syntax.html#end-tags
https://html.spec.whatwg.org/multipage/syntax.html#comments