Added update mapping to API reference and fixed some metadata

_opensearch/rest-api/alias.md

@@ -2,8 +2,7 @@
 layout: default
 title: Alias
 parent: REST API reference
-grand_parent: OpenSearch
-nav_order: 8
+nav_order: 5
 ---
 
 # Alias

_opensearch/rest-api/create-index.md

@@ -2,8 +2,7 @@
 layout: default
 title: Create index
 parent: REST API reference
-grand_parent: OpenSearch
-nav_order: 7
+nav_order: 3
 ---
 
 # Create index

_opensearch/rest-api/update-mapping.md

@@ -0,0 +1,78 @@
+---
+layout: default
+title: Update mapping
+parent: REST API reference
+nav_order: 6
+---
+
+# Update mapping
+
+If you want to update an index's type mappings after its creation, you can do so with the update mapping API operation.
+
+## Example
+
+```json
+PUT /sample-index/_mapping
+
+{
+  "properties": {
+    "age": {
+      "type": "integer"
+    },
+    "occupation":{
+      "type": "text"
+    }
+  }
+}
+```
+
+
+## Path and HTTP methods
+
+```
+PUT /<target-index>/_mapping
+```
+
+You can also use the update mapping operation to update multiple indices with one request.
+
+```
+PUT /<target-index1>,<target-index2>/_mapping
+```
+
+## URL parameters
+
+All update mapping parameters are optional.
+
+Parameter | Data Type | Description
+:--- | :--- | :---
+allow_no_indices | Boolean | If false, the request returns an error if any wildcard expresion or index alias targets any closed or missing indices. Defaults to false.
+expand_wildcards | String | Expands wildcard expressions to different indices. Combine multiple values with commas. Available values are `all` (match all indices), `open` (match open indices), `closed` (match closed indices), `hidden` (match hidden indices), and `none` (do not accept wildcard expressions), which must be used with `open`, `closed`, or both. Default is `open`.
+ignore_unavailable | Boolean | If true, OpenSearch does not include missing or closed indices in the response.
+master_timeout | Time | How long to wait for a connection to the master node. Default is `30s`.
+timeout | Time | How long to wait for the response to return. Default is `30s`.
+write_index_only | Boolean | If true, the specified mappings are applied only to the write index.
+
+## Request body
+
+The request body must contain `properties`, which has all of the mappings that you want to update.
+
+```json
+{
+  "properties":{
+    "color":{
+      "type": "text"
+    },
+    "year":{
+      "type": "integer"
+    }
+  }
+}
+```
+
+## Response
+
+```json
+{
+    "acknowledged": true
+}
+```