Removes redundant monitoring pages (#601)

Author: lcawl

docs/en/stack/index.asciidoc

@@ -22,8 +22,6 @@ include::introduction.asciidoc[]
 
 include::security/index.asciidoc[]
 
-include::monitoring/index.asciidoc[]
-
 include::ml/index.asciidoc[]
 
 include::{es-repo-dir}/ccr/index.asciidoc[]

docs/en/stack/introduction.asciidoc

@@ -12,7 +12,6 @@ For a quick overview, see: https://www.elastic.co/products
 
 * {stack-gs}/get-started-elastic-stack.html[Getting started with the {stack}]
 * <<security-getting-started, Getting Started with Security>>
-* <<xpack-monitoring, Getting Started with Monitoring>>
 * {kibana-ref}/reporting-getting-started.html[Getting Started with Reporting]
 * {kibana-ref}/graph-getting-started.html[Getting Started with Graph]