Update SPIFFE & SPIFFE Steering Committee list

[strideynet]

It looks like we haven't updated this list in a while and that previously, the "SPIFFE" section included a mix of "maintainers of SPIFFE" and "members of the SPIFFE Steering Committee". In this PR, I've added a specific category for members of the SPIFFE Steering Committee to make this a little clearer, and I've updated the list for both categories with those members currently listed in the upstream files.

Checklist for maintainer updates

Note

Delete this template if you're not changing the CSV file

• You've provided a link to documentation where the project has approved the maintainer changes.
• The maintainer(s) also created or updated their LFX Individual Dashboard profile.
• You've sent an email with the list of email address(es) to cncf-maintainer-changes@cncf.io for invitations to Service Desk and mailing lists. You can just mark this complete if you are only removing people.
• Optional: You've also sent a PR with affiliation updates to cncf/gitdm.

[strideynet]

As for

You've sent an email with the list of email address(es) to cncf-maintainer-changes@cncf.io for invitations to Service Desk and mailing lists. You can just mark this complete if you are only removing people.

If you are able to let me know for whom you require the email addresses for, I'll collect that list and email it in.

[mrsabath]

LGTM

[kfox1111]

LGTM