Added the node modules.

node_modules/undici/docs/api/PoolStats.md

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+# Class: PoolStats
+
+Aggregate stats for a [Pool](Pool.md) or [BalancedPool](BalancedPool.md).
+
+## `new PoolStats(pool)`
+
+Arguments:
+
+* **pool** `Pool` - Pool or BalancedPool from which to return stats.
+
+## Instance Properties
+
+### `PoolStats.connected`
+
+Number of open socket connections in this pool.
+
+### `PoolStats.free`
+
+Number of open socket connections in this pool that do not have an active request.
+
+### `PoolStats.pending`
+
+Number of pending requests across all clients in this pool.
+
+### `PoolStats.queued`
+
+Number of queued requests across all clients in this pool.
+
+### `PoolStats.running`
+
+Number of currently active requests across all clients in this pool.
+
+### `PoolStats.size`
+
+Number of active, pending, or queued requests across all clients in this pool.