[SPEC] Backwards-compatible metadata in Gemini

[Stephane Bortzmeyer]

On Tue, Feb 23, 2021 at 05:49:19PM -0500,
 Sean Conner <sean at conman.org> wrote 
 a message of 112 lines which said:

> Having been on this list from the beginning, I can say that the
> majority (I would say nearly all) of the proposals have not gone
> anywhere.  Why?  Because it's easy to make a proposal, it's
> apparently impossible to get anyone to actually *implenent* the damn
> things, even as a "proof-of-concept".  That people are lazy is an
> incredible filter.

The metadata proposal is very simple and I doubt that implementation
is a real obstacle.

Proof-of-concept: I did it in Agunua.

=> https://framagit.org/bortzmeyer/agunua/-/commit/b1eda7c6b4e7e1d210e97f96f51b42a3535ae71f The actual commit, to show it is very simple
=> gemini://gemini.bortzmeyer.org/gemini/metadata.gmi The documentation, and examples

```
% ./agunua --display-metadata gemini://gemini.bortzmeyer.org/gemini/example-metadata-correct.gemini   
{'last-modified': time.struct_time(tm_year=2021, tm_mon=2, tm_mday=24, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=2, tm_yday=55, tm_isdst=-1),
'author': 'Stéphane Bortzmeyer',
'license': 'CC-BY-SA',
'keywords': 'metadata gemini gemtext'}
```