[1.4][DOCS] Fixes SIEM links (#912)

Author: lcawl

docs/products-solutions.asciidoc

@@ -5,10 +5,11 @@ The following Elastic products support ECS out of the box, as of version 7.0:
 
 * {beats-ref}/beats-reference.html[{beats}]
 * {apm-get-started-ref}/overview.html[APM]
-* {siem-guide}/siem-overview.html[Elastic SIEM app]
-* https://www.elastic.co/products/endpoint-security[Elastic Endpoint Security 
+* {security-guide}/es-overview.html[Elastic Security]
+** {security-guide}/siem-field-reference.html[Elastic Security Field Reference] - a list of ECS fields used in the SIEM app
+* https://www.elastic.co/products/endpoint-security[Elastic Endpoint Security
 Server]
-* https://www.elastic.co/guide/en/logs/guide/7.5/logs-app-overview.html[Logs monitoring UI]
+* {logs-guide}/logs-app-overview.html[Logs Monitoring]
 * Log formatters that support ECS out of the box for various languages can be found
   https://github.com/elastic/ecs-logging/blob/master/README.md[here].