Add documentation for "\" special character escape

[jeremygottfried]

I can't find where in the docs indicates that \ escapes special characters.

For example in react jsx, in order to get inline custom props to work, you need \ in front of closing curly braces.

This emmet expression:

div[style={{ padding: '0px'\}}]

Translates to:

<div style={{ padding: '0px'}}></div>

I am assuming this works for escaping any special character, but I can't find any mention of this in the docs.
I searched "literal", "special", "expression", "regex" and "escape" in the cheatsheet with no results. Escaping a special character is a common use case so this should be covered in the docs.