Add missing weighted_routing nodes stats

Closes opensearch-project#7244

Signed-off-by: Lukáš Vlček <[email protected]>

_api-reference/nodes-apis/nodes-stats.md

@@ -53,6 +53,7 @@ script_cache | Statistics about script cache.
 indexing_pressure | Statistics about the node's indexing pressure.
 shard_indexing_pressure | Statistics about shard indexing pressure.
 search_backpressure | Statistics related to search backpressure.
+weighted_routing | Statistics relevant to weighted round robin requests.
 resource_usage_stats | Node-level resource usage statistics, such as CPU and JVM memory.
 admission_control | Statistics about admission control.
 caches | Statistics about caches. 
@@ -82,6 +83,7 @@ The following index metrics are supported:
 - segments
 - translog
 - request_cache
+- recovery
 
 For example, the following query requests statistics for `docs` and `search`:
 
@@ -832,6 +834,7 @@ http.total_opened | Integer | The total number of HTTP connections the node has
 [indexing_pressure](#indexing_pressure) | Object | Statistics related to the node's indexing pressure.
 [shard_indexing_pressure](#shard_indexing_pressure) | Object | Statistics related to indexing pressure at the shard level.
 [search_backpressure]({{site.url}}{{site.baseurl}}/opensearch/search-backpressure#search-backpressure-stats-api) | Object | Statistics related to search backpressure.
+[weighted_routing](#weighted_routing) | Object | Statistics relevant to weighted round robin requests.
 [resource_usage_stats](#resource_usage_stats) | Object | Statistics related to resource usage for the node.
 [admission_control](#admission_control) | Object | Statistics related to admission control for the node.
 [caches](#caches) | Object | Statistics related to caches on the node.
@@ -1282,6 +1285,15 @@ total_rejections_breakup_shadow_mode.throughput_degradation_limits | Integer | T
 enabled | Boolean | Specifies whether the shard indexing pressure feature is turned on for the node.
 enforced | Boolean | If true, the shard indexing pressure runs in enforced mode (there are rejections). If false, the shard indexing pressure runs in shadow mode (there are no rejections, but statistics are recorded and can be retrieved in the `total_rejections_breakup_shadow_mode` object). Only applicable if shard indexing pressure is enabled. 
 
+### `weighted_routing`
+
+The `weighted_routing` object contains statistics about weighted round robin requests. Specifically, it contains a counter of times this node has server a request while it was "zoned out".
+
+Field | Field type | Description
+:--- |:-----------| :---
+stats | Object | Statistics about weighted routing.
+fail_open_count | Integer | Number of times a shard on this node has served a request while the weight for it was set to zero.
+
 ### `resource_usage_stats`
 
 The `resource_usage_stats` object contains the resource usage statistics. Each entry is specified by the node ID and has the following properties.