[SPECS text/gemini] Heading lines proposal

[cage]

Hi!

When studying the documentation about  the text format (and reading the
mailing list messages) i started  to think that the same argumentation
that lead to adding  a space after the list item  marker (the '*') are
valid to the heading marker as well.

For example if i starts a line mentioning an IRC channel like that:

#channel [...]

this would be presented  to the user as an header of  level 1 which is
not.

The same would be true if i mention a tag for a social network.

As for the  list item i think would  be a good idea to add  a space to
the header mark: so from "#" to  "#<space>" and so on for header level
2 and 3.

Not really sure if this is correct, though so i am looking forward for
your comments.

Bye!
C.