Proposal: Standardise `CompletionItemKind: Color` documentation format to always include the hex color at the end

[nik-rev]

Language servers such as vscode-css, tailwindcss, dart-ls which send CompletionItemKind: Color completions, tend to include the hex color at the end of documentation.

This is useful to be able to make colored completion boxes next to each item, as what happens in the Helix editor:

But, it is hard to rely on each language server to properly send the response to contain the hex color at the end of the documentation

This is why it would be useful to make it a part of the LSP spec.