Added update document to REST API reference

_opensearch/rest-api/document-apis/delete-document.md

@@ -2,7 +2,8 @@
 layout: default
 title: Delete document
 parent: Document APIs
-nav_order: 10
+grand_parent: REST API reference
+nav_order: 15
 ---
 
 # Get document

_opensearch/rest-api/document-apis/get-documents.md

@@ -2,6 +2,7 @@
 layout: default
 title: Get document
 parent: Document APIs
+grand_parent: REST API reference
 nav_order: 5
 ---
 

_opensearch/rest-api/document-apis/update-document.md

@@ -0,0 +1,124 @@
+---
+layout: default
+title: Update document
+parent: Document APIs
+grand_parent: REST API reference
+nav_order: 10
+---
+
+# Update document
+
+If you need to update a document's fields in your index, you can use the update document API operation. You can do so by specifying the new data you want in your index or by including a script in your request body, which OpenSearch runs to update the document.
+
+## Example
+
+```json
+POST /sample-index1/_update/1
+{
+  "doc": {
+    "first_name" : "Bruce",
+    "last_name" : "Wayne"
+  }
+}
+```
+
+## Script example
+
+```json
+POST /test-index1/_update/1
+{
+  "script" : {
+    "source": "ctx._source.oldValue += params.newValue",
+    "lang": "painless",
+    "params" : {
+      "newValue" : 10
+    }
+  }
+}
+```
+
+## Path and HTTP methods
+
+```
+POST /<index-name>/_update/<_id>
+```
+
+## URL parameters
+
+Parameter | Type | Description | Required
+:--- | :--- | :--- | :---
+&lt;index-name&gt; | String | Name of the index. | Yes
+&lt;_id&gt; | String | The ID of the document to update. | Yes
+if_seq_no | Integer | Only perform the delete operation if the document's version number matches the specified number. | No
+if_primary_term | Integer | Only perform the delete operation if the document has the specified primary term. | No
+lang | String | Language of the script. Default is `painless`. | No
+require_alias | Boolean | Specifies whether the destination must be an index alias. Default is false. | No
+refresh | Enum | If true, OpenSearch refreshes shards to make the operation visible to searching. Valid options are `true`, `false`, and `wait_for`, which tells OpenSearch to wait for a refresh before executing the operation. Default is false. | No
+retry_on_conflict | Integer | The amount of times OpenSearch should retry the operation if there's a document conflict. Default is 0. | No
+routing | String | Value used to route the operation to a specific shard. | No
+_source | List | Whether to include the `_source` field in the response body. Default is true. | No
+_source_excludes | List | A comma-separated list of source fields to exclude in the query response. | No
+_source_includes | List | A comma-separated list of source fields to include in the query response. | No
+timeout | Time | How long to wait for a response from the cluster. | No
+wait_for_active_shards | String | The number of active shards that must be available before OpenSearch processes the update request. Default is 1 (only the primary shard). Set to `all` or a positive integer. Values greater than 1 require replicas. For example, if you specify a value of 3, the index must have two replicas distributed across two additional nodes for the operation to succeed. | No
+
+## Request body
+
+Your request body must contain the information you want to update your document with. If you just want to replace certain fields in your document, your request body must include a `doc` object, which has the fields you want to update.
+
+```json
+{
+  "doc": {
+    "first_name": "Thomas",
+    "last_name": "Wayne"
+    }
+}
+```
+
+You can also use a script to tell OpenSearch how to update your document.
+
+```json
+{
+  "script" : {
+    "source": "ctx._source.oldValue += params.newValue",
+    "lang": "painless",
+    "params" : {
+      "newValue" : 10
+    }
+  }
+}
+```
+
+## Response
+```json
+{
+  "_index": "sample-index1",
+  "_type": "_doc",
+  "_id": "1",
+  "_version": 3,
+  "result": "updated",
+  "_shards": {
+    "total": 2,
+    "successful": 2,
+    "failed": 0
+  },
+  "_seq_no": 4,
+  "_primary_term": 17
+}
+```
+
+## Response body fields
+
+Field | Description
+:--- | :---
+_index | The name of the index.
+_type | The document's type. OpenSearch only supports one type, which is `_doc`.
+_id | The document's ID.
+_version | The document's version.
+_result | The result of the delete operation.
+_shards | Detailed information about the cluster's shards.
+total | The total number of shards.
+successful | The number of shards OpenSearch succssfully deleted the document from.
+failed | The number of shards OpenSearch failed to delete the document from.
+_seq_no | The sequence number assigned when the document was indexed.
+_primary_term | The primary term assigned when the document was indexed.