docs: Update key to signer-file-key-path in getting starter .witness.yaml

[blhagadorn]

A recent update changed the value for the key location from key to signer-file-key-path, this updates the Getting Started portion to reflect that change:
See https://github.com/testifysec/witness/pull/276/files#diff-a2d81e76a54ef2f17702a8b6de2fac6a61330f3585b3204f0463b3fa880c0f70L16
and current open issue: #287

[blhagadorn]

@mikhailswift I don't think I have permission to add a reviewer, would you be the right person to tag? Thanks

[mikhailswift]

Hi @blhagadorn , thanks for this! John or I are good people to tag for these things. We appreciate the catch on our out of date documentation here.

[mikhailswift]

This is a minor nit, but can you amend your commit message to be inline with the conventional commit spec?

docs: Update key to signer-file-key-path in getting starter .witness.yaml

would be perfect

[mikhailswift]

Sorry for the confusion, I meant the git commit message not the issue title

You should be able to do

git commit --amend and re-word your commit message that way. This will require a git push --force, though. If you'd like I can handle cherry-picking your commit and rewording it, you'll still be the author of the commit :)

[blhagadorn]

no problem, done

[mikhailswift]

Thank you!