add a single "/" (U+002F) character to void element

[root75]

to be more cleann add the / to void element as described in https://www.w3.org/TR/html5/syntax.html#start-tags point 6.

Then, if the element is one of the void elements, or if the element is a foreign element, then there may be a single "/" (U+002F) character. This character has no effect on void elements, but on foreign elements it marks the start tag as self-closing.

[GrimLink]

Plz don't
There is no need to for adding the / to void elements.

There are more than one example why not to do this.
Google styleguide is one example.

Also the w3 mention it as a optional.

Then, if the element is one of the void elements, or if the element is a foreign element, then there may be a single U+002F SOLIDUS character (/). This character has no effect on void elements, but on foreign elements it marks the start tag as self-closing.