Add collector documentation

collectors/cpufreqCpuinfoMetric.md

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+
+## `cpufreq_cpuinfo` collector
+```json
+  "cpufreq_cpuinfo": {}
+```
+
+The `cpufreq_cpuinfo` collector reads the clock frequency from `/proc/cpuinfo` and outputs a handful **cpu** metrics.
+
+Metrics:
+* `cpufreq`

collectors/cpufreqMetric.md

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+## `cpufreq_cpuinfo` collector
+```json
+  "cpufreq": {
+    "exclude_metrics": []
+  }
+```
+
+The `cpufreq` collector reads the clock frequency from `/sys/devices/system/cpu/cpu*/cpufreq` and outputs a handful **cpu** metrics.
+
+Metrics:
+* `cpufreq`

collectors/numastatsMetric.md

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+
+## `numastat` collector
+```json
+  "numastat": {}
+```
+
+The `numastat` collector reads data from `/sys/devices/system/node/node*/numastat` and outputs a handful **memoryDomain** metrics. See: https://www.kernel.org/doc/html/latest/admin-guide/numastat.html
+
+Metrics:
+* `numastats_numa_hit`: A process wanted to allocate memory from this node, and succeeded.
+* `numastats_numa_miss`: A process wanted to allocate memory from another node, but ended up with memory from this node.
+* `numastats_numa_foreign`: A process wanted to allocate on this node, but ended up with memory from another node.
+* `numastats_local_node`: A process ran on this node's CPU, and got memory from this node.
+* `numastats_other_node`: A process ran on a different node's CPU, and got memory from this node.
+* `numastats_interleave_hit`: Interleaving wanted to allocate from this node and succeeded.