Rename directories in /ssn/ tree

I have proposed to do a little reorganising of the repository directory tree.
See [Rearrange repository tree · Issue #86 · w3c/sdw-sosa-ssn (github.com)](https://github.com/w3c/sdw-sosa-ssn/issues/86)
and [Rename directories, add readmes by dr-shorthair · Pull Request #87 · w3c/sdw-sosa-ssn (github.com)](https://github.com/w3c/sdw-sosa-ssn/pull/87)

Linda has approved the pull, but I want to make sure everyone else is aware of the proposal before I merge.

Any objections?
--

Cheers - Simon

scox@ogc.org
dr.shorthair@pm.me

On Boonwurrung land

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