`DocumentSymbol.detail?`: syntax highlighting

The DocumentSymbol interface exposes a detail? field often contains signatures of functions. This is very useful when implementing outline views, as additional information can be provided to the user (the symbol's signature instead of only its name).

However, because DocumentSymbol.detail? is just a string, the client cannot properly colorize the output the same way as is possible for textDocument/signatureHelp. I propose that the textDocument/documentSymbol request be extended with a paramter that makes the DocumentSymbol.detail? of its results MarkupContent, and perhaps even allows to control whether that field should be present at all. A client capability for this is probably the wrong approach, as there are many uses for textDocument/documentSymbol, and not all of them require the more heavy markdown.

Also, perhaps textDocument/documentSymbol should allow lazily requesting the children, similar to the "variables" request of the Debugger Adapter Protocol?

Thoughts and opinions welcome.

Start by reviewing the existing textDocument/documentSymbol request, the DocumentSymbol.detail field, and the textDocument/signatureHelp response. Compare the proposed MarkupContent and lazy-child options, then determine the protocol design and scope with the discussion before making any specification change.