[Backport 2.1] Add Parse JSON processor doc.

_data-prepper/pipelines/configuration/processors/parse-json.md

@@ -1,27 +1,79 @@
 ---
 layout: default
-title: Parse JSON
+title: parse_json
 parent: Processors
 grand_parent: Pipelines
 nav_order: 45
 ---
 
-# Parse JSON
+# parse_json
 
-## Overview
+The `parse_json` processor parses JSON data for an event, including any nested fields. The processor extracts the JSON pointer data and adds the input event to the extracted fields.
 
-The `parse_json` processor parses JSON data for an event, including any nested fields. The following table describes several optional parameters you can configure in the `parse_json` processor. 
 
-Option | Required | Type | Description
-:--- | :--- | :--- | :---
-source | No | String | The field in the `Event` that will be parsed. Default value is `message`.
-destination | No | String | The destination field of the parsed JSON. Defaults to the root of the `Event`. Cannot be `""`, `/`, or any whitespace-only `String` because these are not valid `Event` fields.
-pointer | No | String | A JSON Pointer to the field to be parsed. There is no `pointer` by default, meaning the entire `source` is parsed. The `pointer` can access JSON Array indices as well. If the JSON Pointer is invalid then the entire `source` data is parsed into the outgoing `Event`. If the pointed-to key already exists in the `Event` and the `destination` is the root, then the pointer uses the entire path of the key.
+## Configuration
 
-<!---## Configuration
+You can configure the `parse_json` processor with the following options.
 
-Content will be added to this section.
+| Option | Required | Type | Description |
+| :--- | :--- | :--- | :--- | 
+| `source` | No | String | The field in the `event` that will be parsed. Default value is `message`. |
+| `destination` | No | String | The destination field of the parsed JSON. Defaults to the root of the `event`. Cannot be `""`, `/`, or any whitespace-only `string` because these are not valid `event` fields. |
+| `pointer` | No | String | A JSON pointer to the field to be parsed. There is no `pointer` by default, meaning the entire `source` is parsed. The `pointer` can access JSON array indexes as well. If the JSON pointer is invalid then the entire `source` data is parsed into the outgoing `event`. If the key that is pointed to already exists in the `event` and the `destination` is the root, then the pointer uses the entire path of the key. |
 
-## Metrics
+## Usage
 
-Content will be added to this section.--->
+To get started, create the following `pipeline.yaml` file:
+
+```yaml
+parse-json-pipeline:
+  source:
+    stdin:
+  processor:
+    - parse_json:
+  sink:
+    - stdout:
+```
+
+### Basic example
+
+To test the `parse_json` processor with the previous configuration, run the pipeline and paste the following line into your console, then enter `exit` on a new line:
+
+```
+{"outer_key": {"inner_key": "inner_value"}}
+```
+{% include copy.html %}
+
+The `parse_json` processor parses the message into the following format:
+
+```
+{"message": {"outer_key": {"inner_key": "inner_value"}}", "outer_key":{"inner_key":"inner_value"}}}
+```
+
+### Example with a JSON pointer
+
+You can use a JSON pointer to parse a selection of the JSON data by specifying the `pointer` option in the configuration. To get started, create the following `pipeline.yaml` file:
+
+```yaml
+parse-json-pipeline:
+  source:
+    stdin:
+  processor:
+    - parse_json:
+        pointer: "outer_key/inner_key"
+  sink:
+    - stdout:
+```
+
+To test the `parse_json` processor with the pointer option, run the pipeline, paste the following line into your console, and then enter `exit` on a new line:
+
+```
+{"outer_key": {"inner_key": "inner_value"}}
+```
+{% include copy.html %}
+
+The processor parses the message into the following format:
+
+```
+{"message": {"outer_key": {"inner_key": "inner_value"}}", "inner_key": "inner_value"}
+```