document whether CLI commands do or do not require a git repo to be present #247

I have briefly looked at this:

Any attest command (that is not attest-artifact) basically has three forms:

1. kosli attest junit --fingerprint=${fingerprint} --name=alpha.unit-test ...
2. kosli attest junit ARTIFACT_NAME --artifact-type=docker --name=alpha.unit-test ...
3. kosli attest junit --name=alpha.unit-test ...

Number 1 relies on their being a previous attest-artifact for the supplied fingerprint.

Number 2 also relies on their being a previous attest-artifact for the calculated fingerprint.

Number 3 relies on a git-commit to "commit-join" to a previous attest-artifact for that commit

The kosli-attest artifact command currently requires a git repo to be present.
Eg when you try a command like this, with --repo-root defaulting to . where there is no git repo:

kosli attest artifact ${FILENAME} --fingerprint=${FINGERPRINT} --name=alpha --build-url=https://a.b.c --commit-url=https://a.b.c

or like this

kosli attest artifact ${FILENNAME} --artifact-type=file --name=alpha --build-url=https://a.b.c --commit-url=https://a.b.c

You get the following error:
Error: failed to open git repository at .: repository does not exist

So, at present, it appears that all the kosli-attest command require, directly or indirectly, a git repo to be present