Adding FAQ entry for elastic search (#4821)

* Adding FAQ entry for elastic search

Creating a new category of FAQs for application specific configuration
and adding the first entry for Elasticsearch

Addresses https://github.com/istio/istio/issues/14743

* Making changes to address comments

- Clarifying the text
- Removing unnecessary info
- Adding info on using MTLS
- Adding StatefulSet to .spelling

* Updating the MTLS limit for Release 1.3

* Addressing reviews

Removing spelling entry
Removing Alias for faq file

* Shortened as requested by reviewer

content/en/faq/applications/elasticsearch.md

@@ -0,0 +1,36 @@
+---
+title: Can I run Elasticsearch inside an Istio mesh?
+description: Elasticsearch configuration required for use with Istio
+weight: 50
+keywords: [elasticsearch]
+---
+
+There are two Elasticsearch configuration parameters that need to be
+set appropriately to run Elasticsearch with Istio:
+`network.bind_host` and `network.publish_host`. By default, these
+parameters are set to the `network.host` parameter. If `network.host`
+is set to `0.0.0.0`, Elasticsearch will most likely pick up the pod IP
+as the publishing address and no further configuration will be
+needed.
+
+If the default configuration does not work, you can set the
+`network.bind_host` to `0.0.0.0` or `localhost` (`127.0.0.1`) and
+`network.publish_host` to the pod IP. For example:
+
+{{< text yaml >}}
+...
+containers:
+- name: elasticsearch
+  image: docker.elastic.co/elasticsearch/elasticsearch:7.2.0
+  env:
+    - name: network.bind_host
+      value: 127.0.0.1
+    - name: network.publish_host
+      valueFrom:
+        fieldRef:
+          fieldPath: status.podIP
+   ...
+{{< /text >}}
+
+Refer to [Network Settings for Elasticsearch](https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-network.html#modules-network)
+for more information.

content/en/faq/applications/index.md

@@ -0,0 +1,8 @@
+---
+title: Applications FAQ
+linktitle: Applications
+description: Application Specific Q & A.
+weight: 30
+layout: faq
+icon: faq
+---