Deprecate govuk-button--disabled class

[querkmachine]

Notes the deprecation of the govuk-button--disabled class in Sass and the changelog.

Closes #2271.

[colinrotherham]

Looks good to me @querkmachine 🙌

Assuming that the Deprecating a CSS class docs are definitely correct

@36degrees I can see the docs landed recently in #2679, can we check if the CSS class example was supposed to be double-slashed?

// @deprecated
.govuk-foo-old-class-name {
  foo: bar;
}

[36degrees]

Yeah, I think so – this isn't SassDoc as SassDoc isn't designed to be used to document CSS.

Appreciate it's confusing – open to suggestions if there's a better way of doing it.

[colinrotherham]

Yeah, I think so – this isn't SassDoc as SassDoc isn't designed to be used to document CSS.

Appreciate it's confusing – open to suggestions if there's a better way of doing it.

@36degrees Brill, no just checking

Sass syntax highlighting kicks in at triple-slash so it seemed like the sensible answer. We don't have new lines below comments in those docs (but do across our Sass files) so perhaps that's the only inconsistency?