Added a new user company

[jimaek]

Reason for this PR

Added appfleet as the second company using firecracker to go along with fly.io. I hope this is fine as there was no mention of fly.io having special status

Description of changes

Just added a small link

License acceptance

By submitting this pull request, I confirm that my contribution is made under
the terms of the MIT-0 [1] license.

[1] https://github.com/aws/mit-0

PR checklist

[Author TODO: Meet these criteria & check the boxes.]
[Reviewer TODO: Verify checked boxes. Request changes if criteria not met]

• The reason for this PR is clearly provided (issue no. or explanation).
• The description of changes is clear and encompassing.
• All commits in this PR are signed (git commit -s).

[raduweiss]

We were not aware that Firecracker is used in appfleet, and we're excited to find out! We definitely want to add it to the list. However, at this point I think that paragraph needs to be reshuffled a bit. I'll add a review comment shortly with a proposal.

[raduweiss]

I think the lines between "used by"/"integrated with" are quite blurry at this point. Initially, we tried to differentiate between open source integrations and other things, but that's just confusing now, I think.

So instead of
Firecracker is integrated with Kata Containers, Open Nebula, UniK, Weave FireKube (via Weave Ignite ), and containerd via firecracker-containerd. It's also used by fly.io as well as appfleet.

we could go with
Firecracker is used by/integrated with (in alpahbetical order): appfleet, containerd via firecracker-containerd, fly.io, Kata Containers, Open Nebula, UniK, and Weave FireKube (via Weave Ignite ).
What do folks think?

[albert0marti]

I've just included these changes in #9 (also at the FAQ section)

[raduweiss]

Changes here-in are picked up by @albert0marti in #9. I'll close this and work to process that PR. Feel free to reopen if that's not aligned with the intent here.