docs: image and registry config guide need to be updated

[ZhangShuaiyi]

Description

• Add CRI Service plugin type #9681 Moves registry configuration to io.containerd.cri.v1.images
• Split CRI image service from GRPC handler #9152 Adds ImageConfig

I want to update the docs.

• Update registry config guide in docs.
• Update images config guide in docs.

Steps to reproduce the issue

No response

Describe the results you received and expected

We need to update config guide in docs.

What version of containerd are you using?

v2.0.0-rc.0

Any other relevant information

No response

Show configuration if it is related to CRI plugin.

version = 2

[plugins."io.containerd.grpc.v1.cri".registry]
config_path = "/etc/containerd/certs.d"