[css-2024] Add some additional content

[UnVuTWFu]

This is not right:

CSS Syntax Level 3 [CSS-SYNTAX-3]
Replaces CSS2§4.1, CSS2§4.2, CSS2§4.4, and CSS2§G, redefining how CSS is parsed.

and should be modified to:

CSS Syntax Level 3 [CSS-SYNTAX-3]
Replaces CSS2§4.1 excepting §4.1.3, CSS2§4.2, CSS2§4.4, and CSS2§G, redefining how CSS is parsed.

because CSS2 §4.1.3 is referenced in [SELECTORS-3]

Characters in Selectors can be escaped with a backslash according to the same escaping rules as CSS. [CSS21].

[tabatkins]

Selectors 3 was replaced by Selectors 4, which is based on the Syntax parsing model. The CSS2 parsing rules are no longer part of CSS.

[svgeesus]

Selectors 3 was replaced by Selectors 4,

Selectors 4 is in Modules with Rough Interoperability, not in Official Definition.

[UnVuTWFu]

Selectors 3 was replaced by Selectors 4, which is based on the Syntax parsing model. The CSS2 parsing rules are no longer part of CSS.

right,but even in Selector 4 §3.7. Characters and case sensitivity,it still references the escape rules of CSS2 §4.1.3

Code points in Selectors can be escaped with a backslash according to the same escaping rules as CSS. [CSS21] Note that escaping a code point “cancels out” any special meaning it may have in Selectors. For example, the selector #foo>a contains a combinator, but #foo>a instead selects an element with the id foo>a.

so the snapshot2024 page seems to need modification