add slurm_cgroup Collector

collectors/slurmCgroupMetric.md

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+<!--
+---
+title: Slurm cgroup metric collector
+description: Collect per-core memory and CPU usage for SLURM jobs from cgroup v2
+categories: [cc-metric-collector]
+tags: ['Admin']
+weight: 3
+hugo_path: docs/reference/cc-metric-collector/collectors/slurm_cgroup.md
+---
+-->
+
+## `slurm_cgroup` collector
+
+The `slurm_cgroup` collector reads job-specific resource metrics from the cgroup v2 filesystem and provides **hwthread** metrics for memory and CPU usage of running SLURM jobs.  
+
+### Example configuration
+
+```json
+"slurm_cgroup": {
+  "cgroup_base": "/sys/fs/cgroup/system.slice/slurmstepd.scope",
+  "exclude_metrics": [
+    "job_sys_cpu",
+    "job_mem_limit"
+  ]
+}
+```
+
+* The `cgroup_base` parameter (optional) can be set to specify the root path to SLURM job cgroups. The default is `/sys/fs/cgroup/system.slice/slurmstepd.scope`.
+* The `exclude_metrics` array can be used to suppress individual metrics from being sent to the sink.
+
+### Reported metrics
+
+All metrics are available **per hardware thread** :
+
+* `job_mem_used` (`unit=Bytes`): Current memory usage of the job
+* `job_max_mem_used` (`unit=Bytes`): Peak memory usage
+* `job_mem_limit` (`unit=Bytes`): Cgroup memory limit
+* `job_user_cpu` (`unit=%`): User CPU utilization percentage
+* `job_sys_cpu` (`unit=%`): System CPU utilization percentage
+
+Each metric has tags:
+
+* `type=hwthread`
+* `type-id=<core_id>`
+
+### Limitations
+
+* **cgroups v2 required:** This collector only supports systems running with cgroups v2 (unified hierarchy).