Move “Custom code” in 3.7 to 3.18

[hidde]

If we update 3.18, Preferred Code to:

Avoid the use of deprecated, proprietary, non-standard, or outdated formats and web standards. Always adopt up-to-date, widely recognized standards that offer equivalent or improved functionality. Such code may be used to meet a documented customer need only if there is a justifiable benefit that cannot otherwise be met (such as compatibility, accessibility, or emissions reduction). Also, don't serve polyfills to modern browsers.

(update in bold)

we could remove 3.7 “Custom code”.

[airbr]

This makes sense to me but may be relevant to other concerns. 3.7 Code must follow good semantic practices is good, but removing a guideline might make things simpler and better?

Prefer using standard HTML elements and attributes. Only use custom elements or Web Components if you cannot utilize native HTML elements or if you need tightly regulated control over the implementation of design system components..

I found this section of 3.7 particularly helpful, in its language about when to use web components. We could keep this somewhere. Also, there is an extra period in the sentence end.

@AlexDawsonUK