Add api-ls shared attribute (#3155)

Author: lcawl

shared/versions/stack/8.17.asciidoc

@@ -73,4 +73,5 @@ Synthetics
 API URLs
 ////
 :api-kibana:           https://www.elastic.co/docs/api/doc/kibana/v8
-:api-es:               https://www.elastic.co/docs/api/doc/elasticsearch/v8
+:api-es:               https://www.elastic.co/docs/api/doc/elasticsearch/v8
+:api-ls:               https://www.elastic.co/docs/api/doc/logstash

shared/versions/stack/8.x.asciidoc

@@ -72,4 +72,5 @@ Synthetics
 API URLs
 ////
 :api-kibana:           https://www.elastic.co/docs/api/doc/kibana/v8
-:api-es:               https://www.elastic.co/docs/api/doc/elasticsearch/v8
+:api-es:               https://www.elastic.co/docs/api/doc/elasticsearch/v8
+:api-ls:               https://www.elastic.co/docs/api/doc/logstash

shared/versions/stack/master.asciidoc

@@ -73,6 +73,7 @@ API URLs
 ////
 :api-kibana:           https://www.elastic.co/docs/api/doc/kibana
 :api-es:               https://www.elastic.co/docs/api/doc/elasticsearch
+:api-ls:               https://www.elastic.co/docs/api/doc/logstash
 
 ////
 Feature flags