[stable/kibana] Add upgrading section to README (#13720)

* Add upgrading section to README

Signed-off-by: Naseem <naseemkullah@gmail.com>

* Update stable/kibana/README.md

Co-Authored-By: Cédric de Saint Martin <cedric@desaintmartin.fr>
Signed-off-by: Naseem <naseemkullah@gmail.com>

* Bump major version

Signed-off-by: Naseem <naseemkullah@gmail.com>

stable/kibana/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v1
 name: kibana
-version: 2.3.1
+version: 3.0.0
 appVersion: 6.7.0
 description: Kibana is an open source data visualization plugin for Elasticsearch
 icon: https://raw.githubusercontent.com/elastic/kibana/master/src/ui/public/icons/kibana-color.svg

stable/kibana/README.md

@@ -138,3 +138,9 @@ $ helm install stable/kibana --name my-release -f values.yaml
 ## Dasboard import
 
 -   A dashboard for dashboardImport.dashboards can be a JSON or a download url to a JSON file.
+
+## Upgrading
+
+### To 2.3.0
+
+The default value of `elasticsearch.url` (for kibana < 6.6) has been removed in favor of `elasticsearch.hosts` (for kibana >= 6.6).

stable/kibana/values.yaml

@@ -11,10 +11,10 @@ commandline:
   args: []
 
 env: {}
-  # All Kibana configuration options are adjustable via env vars.
-  # To adjust a config option to an env var uppercase + replace `.` with `_`
-  # Ref: https://www.elastic.co/guide/en/kibana/current/settings.html
-  #
+  ## All Kibana configuration options are adjustable via env vars.
+  ## To adjust a config option to an env var uppercase + replace `.` with `_`
+  ## Ref: https://www.elastic.co/guide/en/kibana/current/settings.html
+  ## For kibana < 6.6, use ELASTICSEARCH_URL instead
   # ELASTICSEARCH_HOSTS: http://elasticsearch-client:9200
   # SERVER_PORT: 5601
   # LOGGING_VERBOSE: "true"
@@ -25,6 +25,7 @@ files:
     ## Default Kibana configuration from kibana-docker.
     server.name: kibana
     server.host: "0"
+    ## For kibana < 6.6, use elasticsearch.url instead
     elasticsearch.hosts: http://elasticsearch:9200
 
     ## Custom config properties below