[Spec] <META> in the response header is too vague

[Solene Rapenne]

From the specification in "3.1 Response headers" it seems there are no current limitation to what could be used in META:

<STATUS><SPACE><META><CR><LF> 

> <META> is a UTF-8 encoded string of maximum length 1024 bytes,
> whose meaning is <STATUS> dependent.

There is currently only the content type in it and possibiliy the lang metadata added for text/gemini types.

Maybe I missed something about it in the spec, but it's really vague,

- Is it ok to add many data in the response and up to the client to do something with them?
- Should clients be strict and error in case of unknown fields?
- What is planned for? It has 1024 bytes and doesn't use much, it seems to be ready for something else "just in case".