Adds discrete attributes to installation and upgrade guide

Author: lcawl

docs/en/install-upgrade/installing-stack.asciidoc

@@ -8,6 +8,7 @@ Kibana {version}, and Logstash {version}.
 
 If you're upgrading an existing installation, see <<upgrading-elastic-stack, Upgrading the Elastic Stack>> for information about how to ensure compatibility with {version}.
 
+[discrete]
 [[install-order-elastic-stack]]
 === Installation Order
 
@@ -22,6 +23,7 @@ Install the Elastic Stack products you want to use in the following order:
 Installing in this order ensures that the components each product depends
 on are in place.
 
+[discrete]
 [[install-elastic-stack-for-elastic-cloud]]
 === Installing on Elastic Cloud
 

docs/en/install-upgrade/upgrading-stack.asciidoc

@@ -30,6 +30,7 @@ remove or reindex them on your 5.n cluster before upgrading to {version}. The in
 Kibana and {xpack} indices and the default Beats and Logstash mapping templates
 also need to be updated to work with {version}.
 
+[discrete]
 === Preparing to upgrade
 
 Before upgrading the Elastic Stack to {version}:
@@ -95,6 +96,7 @@ upgrade process. See
 IMPORTANT: Test upgrades in a dev environment before upgrading your
 production cluster.
 
+[discrete]
 [[upgrade-order-elastic-stack]]
 === Upgrade order
 
@@ -112,6 +114,7 @@ for your Logstash instances and Beats agents. We recommend upgrading Logstash
 and Beats as soon as possible to take advantage of performance improvements
 and other enhancements.
 
+[discrete]
 === Upgrading to 6.3
 Starting in 6.3, the default distributions of Elasticsearch, Logstash, and Kibana
 include {xpack} and a free Basic license that never expires.
@@ -149,9 +152,9 @@ POST _xpack/license/start_trial
 The 30-day trial enables you to try out the full set of platinum features,
 including security, machine learning, alerting, graph capabilities, and more.
 
-[role="xpack"]
+[discrete]
 [[xpack-stack-upgrade]]
-=== Upgrading from 5.6
+=== [xpack]#Upgrading from 5.6#
 
 {xpack} 5.6 provides migration and upgrade APIs for Elasticsearch and a
 Upgrade Assistant UI for Kibana. These tools are included with the trial
@@ -208,6 +211,7 @@ single-type format compatible with Elasticsearch 6.x.
 . Once you've resolved all of the migration issues, perform
 a {ref}/rolling-upgrades.html[rolling upgrade] from Elasticsearch 5.6 to {version}.
 
+[discrete]
 [[oss-stack-upgrade]]
 === Upgrading from a pre-5.6 installation
 
@@ -229,6 +233,7 @@ modifications to the document data and metadata during reindexing.
 . Use the {ref}/indices-aliases.html[_aliases] API to add the name of the 2.x
 index as alias for the new index and delete the 2.x index.
 
+[discrete]
 [[upgrade-internal-indices]]
 ==== Upgrading internal indices for {major-version}
 
@@ -270,6 +275,7 @@ internal indices using the `_xpack/migration/upgrade` API.
 TIP: Once you upgrade the `.kibana` index, you can run Kibana and use the
 {xpack} Reindex Helper UI to upgrade the other indices.
 
+[discrete]
 [[upgrade-elastic-stack-for-elastic-cloud]]
 === Upgrading on Elastic Cloud