update sample outputs of key list cmd to match singularity PR 1957, from sylabs 174

[JasonYangShadow]

This fixes a subpart of #239 by merging

• update sample outputs of key list cmd to match singularity PR 1957 sylabs/singularity-userdocs#174
  which fixed
• improve key list output sylabs/singularity#1957

The original PR description was:

sylabs/singularity#1957 changes the format of the output of singularity key list. This PR updates the sample outputs of this command contained in the User Guide to match this change.

[DrDaveD]

Looks OK other than the DCO check.

[JasonYangShadow]

• Fixes sub-issue of Import sylabs userdocs PRs #239

https://github.com/sylabs/singularity-userdocs/pull/174/commits
the original author does not sign off commits.

[DrDaveD]

the original author does not sign off commits.

That's normal. You need to sign off on it instead.

For the description, please follow the pattern in one of mine like #244

[DrDaveD]

If a cherry-pick succeeds without any conflicts, it doesn't give you the opportunity to add sign-off, but you can use the -s option on cherry-pick to add it or you can use -n to not automatically commit. Watch out though with the latter that it doesn't lose the original author, I think sometimes at least it does. In that case you should add back the original author with the commit --author option.