[DOC] Create Dashboards quickstart (opensearch-project#2409)

Create new documentation site pages and content for foundational user documentation 
---------

Signed-off-by: vagimeli <[email protected]>

Author: vagimeli

_dashboards/discover/dql.md

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+---
+layout: default
+title: Using Dashboards Query Language
+parent: Exploring data with Discover
+nav_order: 40
+redirect_from:
+  - /dashboards/dql/
+---
+
+# Using Dashboards Query Language
+
+Dashboards Query Language (DQL) is a simple text-based query language for filtering data in OpenSearch Dashboards. Similar to [Query DSL]({{site.url}}{{site.baseurl}}/opensearch/query-dsl/index), DQL uses an HTTP request body. For example, to display your site visitor data for a host in the United States, you would enter `geo.dest:US` in the search field, as shown in the following image.
+
+<img src="{{site.url}}{{site.baseurl}}/images/dashboards/dql-interface.png" alt="Search term using DQL toolbar in Dashboard" width="500">
+
+Before you can search data in Dashboards, you must index it. In OpenSearch, the basic unit of data is a JSON document. Within an index, OpenSearch identifies each document using a unique ID. To learn more about indexing in OpenSearch, see [Index data]({{site.url}}{{site.baseurl}}/opensearch/index-data).
+{: .note purple}
+
+## Searching with terms queries
+
+The most basic query specifies the search term, for example:
+
+```
+host:www.example.com
+```
+
+To access an object's nested field, list the complete path to the field separated by periods. For example, use the following path to retrieve the `lat` field in the `coordinates` object:
+
+```
+coordinates.lat:43.7102
+```
+
+DQL supports leading and trailing wildcards, so you can search for any terms that match your pattern, for example:
+
+```
+host.keyword:*.example.com/*
+```
+
+To check whether a field exists or has any data, use a wildcard to see whether Dashboards returns any results,for example:
+
+```
+host.keyword:*
+```
+
+## Searching with Boolean queries
+
+To mix and match or combine multiple queries for more refined results, you can use the Boolean operators `and`, `or`, and `not`. DQL is not case sensitive, so `AND` and `and` are the same, for example: 
+
+```
+host.keyword:www.example.com and response.keyword:200
+```
+
+You also can use multiple Boolean operators in one query, for example:
+
+```
+geo.dest:US or response.keyword:200 and host.keyword:www.example.com
+```
+
+Remember that Boolean operators follow the logical precedence order of `not`, `and`, and `or`, so if you have an expression like the one in the preceding example, `response.keyword:200 and host.keyword:www.example.com` is evaluated first.
+
+To avoid confusion, use parentheses to dictate the order in which you want to evaluate operands. If you want to evaluate `geo.dest:US or response.keyword:200` first, you can use an expression like the following:
+
+```
+(geo.dest:US or response.keyword:200) and host.keyword:www.example.com
+```
+
+## Querying dates and ranges
+
+DQL supports numeric inequalities, for example, `bytes >= 15 and memory < 15`.
+
+You can use the same method to find a date before or after the date specified in the query. `>` indicates a search for a date after the specified date, and `<` returns dates before the specified date, for example, `@timestamp > "2020-12-14T09:35:33`.
+
+## Querying nested fields
+
+Searching a document with [nested fields]({{site.url}}{{site.baseurl}}/opensearch/supported-field-types/nested/) requires you to specify the full path of the field to be retrieved. In the following example document, the `superheroes` field has nested objects:
+
+```json
+{
+ "superheroes":[
+    {
+      "hero-name": "Superman",
+      "real-identity": "Clark Kent",
+      "age": 28
+    },
+    {
+      "hero-name": "Batman",
+      "real-identity": "Bruce Wayne",
+      "age": 26
+    },
+    {
+      "hero-name": "Flash",
+      "real-identity": "Barry Allen",
+      "age": 28
+    },
+    {
+      "hero-name": "Robin",
+      "real-identity": "Dick Grayson",
+      "age": 15
+    }
+  ]
+}
+```
+{% include copy.html %}
+
+To retrieve documents that match a specific field using DQL, specify the field, for example:
+
+```
+superheroes: {hero-name: Superman}
+```
+{% include copy.html %}
+
+To retrieve documents that match multiple fields, specify all the fields, for example:
+
+```
+superheroes: {hero-name: Superman} and superheroes: {hero-name: Batman}
+```
+{% include copy.html %}
+
+You can combine multiple Boolean and range queries to create a more refined query, for example:
+
+```
+superheroes: {hero-name: Superman and age < 50}
+```
+{% include copy.html %}
+
+## Querying doubly nested objects 
+
+If a document has doubly nested objects (objects nested inside other objects), retrieve a field value by specifying the full path to the field. In the following example document, the `superheroes` object is nested inside the `justice-league` object:
+
+```json
+{
+"justice-league": [
+{
+"superheroes":[
+{
+"hero-name": "Superman",
+"real-identity": "Clark Kent",
+"age": 28
+},
+{
+"hero-name": "Batman",
+"real-identity": "Bruce Wayne",
+"age": 26
+},
+{
+"hero-name": "Flash",
+"real-identity": "Barry Allen",
+"age": 28
+},
+{
+"hero-name": "Robin",
+"real-identity": "Dick Grayson",
+"age": 15
+}
+]
+}
+]
+}
+```
+{% include copy.html %}
+
+The following image shows the query result using the example notation `justice-league.superheroes: {hero-name:Superman}`.
+
+<img src="{{site.url}}{{site.baseurl}}/images/dashboards/dql-query-result.png" alt="DQL query result" width="1000">

_dashboards/discover/time-filter.md

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+---
+layout: default
+title: Setting the time filter
+parent: Exploring data with Discover
+nav_order: 10
+---
+
+# Setting the time filter
+
+You can change the time range to display dashboard data over minutes, hours, days, weeks, months, or years.
+
+The default time range is **Last 15 minutes**. You can change the time range at the dashboard level or under **Stack Management > Advanced Settings > Time filter defaults**. 
+{: .note}
+
+To change the time range at the dashboard level, perform the following steps:
+
+1. Select the calendar icon.
+2. Select one of the time filter options, as shown in the following image:
+   - **Quick select:** Choose a time based on the last or next number of seconds, minutes, hours, days, or another time unit. 
+   - **Commonly used:** Choose a common time range like **Today**, **Last 7 days**, or **Last 30 days**. 
+   - **Recently used date ranges:** Select a previously used time range.
+   - **Refresh every:** Set an automatic refresh period.
+
+    <img src="{{site.url}}{{site.baseurl}}/images/dashboards/time-range.png" alt="Time range interface" width="400"/>
+
+3. Choose **Show dates** to set start and end times, and then select anywhere inside the toolbar to access the time filter pop-up window, as shown in the following image.
+
+   <img src="{{site.url}}{{site.baseurl}}/images/dashboards/time-filter-popup.png" alt="Time filter pop-up window" width="400"/>
+
+4. Select **Absolute**, **Relative**, or **Now** and specify ranges.
+5. Choose **Update** to apply changes, as shown in the following image.
+
+   <img src="{{site.url}}{{site.baseurl}}/images/dashboards/start-end-time.png" alt="Start and end times interface" width="400"/>