adding further description of KeyManager

[ChaosInTheCRD]

Description of the change
I began some work to try and make a KeyManager plugin that handed off signing to a CA service in the hope that said service could make policy decisions based on the SVID being presented (e.g., X.509 Certificate Signing request). Of course this does not work, and I misled myself. I am hopeful that this PR will make it more clear for others that hope to do the same thing.

[netlify]

✅ Deploy Preview for spiffe ready!

Name	Link
🔨 Latest commit	789297e
🔍 Latest deploy log	https://app.netlify.com/sites/spiffe/deploys/64e718f0bc42ea0008f615ff
😎 Deploy Preview	https://deploy-preview-285--spiffe.netlify.app/docs/latest/planning/extending
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[sanderson042]

Hi @ChaosInTheCRD - Thank you for the PR! My day job is editing and writing software documentation, so here's my take on the wording. Someone else can review the meaning.

[sanderson042]

Thanks for making the suggested changes!

[amartinezfayo]

Thank you @ChaosInTheCRD for this enhancement in the documentation.
While I think that a clarification about how the Key Manager operates is needed, I would probably word this little differently because IMO it puts some negative emphasis that's not the intent of the section.
Let me discuss this with the SPIRE maintainers team and get back here with the feedback.

Thanks again!

[ChaosInTheCRD]

Thank you @ChaosInTheCRD for this enhancement in the documentation.

While I think that a clarification about how the Key Manager operates is needed, I would probably word this little differently because IMO it puts some negative emphasis that's not the intent of the section.

Let me discuss this with the SPIRE maintainers team and get back here with the feedback.

Thanks again!

Hey! No problem, it wasn't my intention to make anything sound negative, just to draw a line between what the key manager is and what the upstream authority is ☺️