Documentation for Debugging Snapshotter (#6859)

* Documentation for Debugging Snapshotter

* Documentation for Debugging Snapshotter

* Documentation for Debugging Snapshotter

cluster-autoscaler/debuggingsnapshot/README.md

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+# Debugging Snapshotter
+It's a tool to visualize the internal state of cluster-autoscaler at a point in time to help debug autoscaling issues.
+
+### Requirements
+Require Cluster-autoscaler versions **1.24+**
+
+#### What data snapshotter can capture?
+https://github.com/kubernetes/autoscaler/blob/8cf630a3e33ed3656cb4e669461bec197b77f2bb/cluster-autoscaler/debuggingsnapshot/debugging_snapshot.go#L60C1-L71C1
+```go
+type DebuggingSnapshotImpl struct {
+	NodeList                      []*ClusterNode          `json:"NodeList"`
+	UnscheduledPodsCanBeScheduled []*v1.Pod               `json:"UnscheduledPodsCanBeScheduled"`
+	Error                         string                  `json:"Error,omitempty"`
+	StartTimestamp                time.Time               `json:"StartTimestamp"`
+	EndTimestamp                  time.Time               `json:"EndTimestamp"`
+	TemplateNodes                 map[string]*ClusterNode `json:"TemplateNodes"`
+}
+
+```
+## Development
+Add the following flag to your cluster-autoscaler configuration to enable the snapshotter feature.
+```
+--debugging-snapshot-enabled=true
+```
+To access the sapshot from the command line, use the following command:
+```
+ curl http://127.0.0.1:8085/snapshotz > FIlE_NAME.json
+```
+How to nevigate JSON file?
+
+```sh
+cat FIlE_NAME.json | jq 'keys'
+cat FIlE_NAME.json | jq '.NodeList | keys' //to see how many nodes are running
+cat FIlE_NAME.json | jq '.TempletsNodes | keys' //to see templated nodes
+cat FIlE_NAME.json | jq '.UnscheduledPodsCanBeScheduled | keys' //to see unscheduled pods that can be scheduled
+```