Port [Rancher2] Docs: Migrate etcd troubleshooting guide from RKE/Docker to RKE2/K3s/containerd #2203

[LucasSaintarbor]

Port rancher/rancher-docs#2203.

[btat]

I'm not sure if we want to handle as part of this PR, but I think tabs should have been suggested/applied in the Community PR. There are ~15 instances on the page of how to do something with/for RKE2 immediately followed by the K3s version. Users need to manually "filter" all of these, but we could handle it automatically and so it's a better user experience.

[btat]

We should be using the native AsciiDoc admonition syntax.

Edit: Looks like the DIY admonition originates from the Community PR and needs to be fixed too.

Suggested change

	____
	=== ⚠️ *Warning*
	K3s does not include `etcdctl` in the system PATH. If you need to perform etcd troubleshooting on a K3s cluster, you may need to install it or locate it within the K3s data directory.
	____
	[WARNING]
	====
	K3s does not include `etcdctl` in the system PATH. If you need to perform etcd troubleshooting on a K3s cluster, you may need to install it or locate it within the K3s data directory.
	====

[btat]

Is putting this text in a blockquote necessary? The following paragraph (Since standard HTTP...) also seems like a continuation of the topic quoted.

I think this should just be regular text?

Edit: Looks like this originates from the Community PR. If this is changed, it should apply there too.

Suggested change

	____
	In modern versions of Kubernetes, the etcd database (versions 3.5 and newer) introduced significant architectural changes regarding network traffic handling. Previously, etcd permitted standard HTTP REST requests on its primary client port (`2379`). However, to enhance performance and security, etcd 3.5+ strictly enforces the gRPC protocol on this port.
	If you attempt to use standard HTTP tools like `curl` to test connectivity on port `2379`, the etcd server will automatically terminate the connection or return an error. This behavior often leads administrators to misinterpret the result as a closed port or a node failure.
	____
	In modern versions of Kubernetes, the etcd database (versions 3.5 and newer) introduced significant architectural changes regarding network traffic handling. Previously, etcd permitted standard HTTP REST requests on its primary client port (`2379`). However, to enhance performance and security, etcd 3.5+ strictly enforces the gRPC protocol on this port.
	If you attempt to use standard HTTP tools like `curl` to test connectivity on port `2379`, the etcd server will automatically terminate the connection or return an error. This behavior often leads administrators to misinterpret the result as a closed port or a node failure.