publishing our first crates to crates.io?

Dear Community Group,

this is just to draw your attention on the PR I just opened

https://github.com/w3c-cg/r2c2/pull/14

Per our charter <https://github.com/w3c-cg/r2c2/blob/main/Charter.md>, I 
labelled this PR as 'request-publication', to propose that we publish 
v0.1.0 of crates `r2c2_statement` and `r2c2r_statement_validation`.

Citing the PR message:

There has not been much interaction on the repository, so if you think 
the current code does not go in the right direction, now is the time to 
speak up :)

If you think the code /does/ go in the right direction, please also 
support this PR (approve, thumbs up, "+1"...). I would rather have 
/explicit/ group support for actually publishing the crate.

   best