Add API URL variable

Author: lcawl

docs/docset.yml

@@ -40,6 +40,7 @@ subs:
   ece:   "Elastic Cloud Enterprise"
   eck:   "Elastic Cloud on Kubernetes"
   ech:   "Elastic Cloud Hosted"
+  es-apis: https://www.elastic.co/docs/api/doc/elasticsearch/
   es-issue:   "https://github.com/elastic/elasticsearch/issues/"
   serverless-full:   "Elastic Cloud Serverless"
   serverless-short:   "Serverless"

docs/reference/elasticsearch/rest-apis/api-conventions.md

@@ -396,7 +396,7 @@ Each filter can be one of the following:
 * a pattern, using `*` wildcards, which adds all nodes to the subset whose name, address, or hostname matches the pattern.
 * `master:true`, `data:true`, `ingest:true`, `voting_only:true`, `ml:true`, or `coordinating_only:true`, which respectively add to the subset all master-eligible nodes, all data nodes, all ingest nodes, all voting-only nodes, all machine learning nodes, and all coordinating-only nodes.
 * `master:false`, `data:false`, `ingest:false`, `voting_only:false`, `ml:false`, or `coordinating_only:false`, which respectively remove from the subset all master-eligible nodes, all data nodes, all ingest nodes, all voting-only nodes, all machine learning nodes, and all coordinating-only nodes.
-* a pair of patterns, using `*` wildcards, of the form `attrname:attrvalue`, which adds to the subset all nodes with a [custom node attribute](/reference/elasticsearch/configuration-reference/node-settings#custom-node-attributes) whose name and value match the respective patterns. Custom node attributes are configured by setting properties in the configuration file of the form `node.attr.attrname: attrvalue`.
+* a pair of patterns, using `*` wildcards, of the form `attrname:attrvalue`, which adds to the subset all nodes with a [custom node attribute](/reference/elasticsearch/configuration-reference/node-settings.md#custom-node-attributes) whose name and value match the respective patterns. Custom node attributes are configured by setting properties in the configuration file of the form `node.attr.attrname: attrvalue`.
 
 Node filters run in the order in which they are given, which is important if using filters that remove nodes from the set.
 For example, `_all,master:false` means all the nodes except the master-eligible ones.