add documentation for ws_db_event_categories

Author: saravanan30erd

website/aws.erb

@@ -116,6 +116,9 @@
                         <li<%= sidebar_current("docs-aws-datasource-db-cluster-snapshot") %>>
                           <a href="/docs/providers/aws/d/db_cluster_snapshot.html">aws_db_cluster_snapshot</a>
                         </li>
+                        <li<%= sidebar_current("docs-aws-datasource-db-event-categories") %>>
+                          <a href="/docs/providers/aws/d/db_event_categories.html">aws_db_event_categories</a>
+                        </li>
                         <li<%= sidebar_current("docs-aws-datasource-db-instance") %>>
                             <a href="/docs/providers/aws/d/db_instance.html">aws_db_instance</a>
                         </li>

website/docs/d/db_event_categories.html.markdown

@@ -0,0 +1,45 @@
+---
+layout: "aws"
+page_title: "AWS: aws_db_event_categories"
+sidebar_current: "docs-aws-datasource-db-event-categories"
+description: |-
+    Provides a list of DB Event Categories which can be used to pass values into DB Event Subscription.
+---
+
+# Data Source: aws_db_event_categories
+
+## Example Usage
+
+List the event categories of all the RDS resources. 
+
+```hcl
+data "aws_db_event_categories" "example" {}
+
+output "example" {
+  value = "${data.aws_db_event_categories.example.event_categories}"
+}
+```
+
+List the event categories specific to the RDS resource `db-snapshot`.
+
+```hcl
+data "aws_db_event_categories" "example" {
+  source_type = "db-snapshot"
+}
+
+output "example" {
+  value = "${data.aws_db_event_categories.example.event_categories}"
+}
+```
+
+## Argument Reference
+
+The following arguments are supported:
+
+* `source_type` - (Optional) The type of source that will be generating the events. Valid options are db-instance, db-security-group, db-parameter-group, db-snapshot, db-cluster or db-cluster-snapshot.
+
+## Attributes Reference
+
+In addition to all arguments above, the following attributes are exported:
+
+* `event_categories` - A list of the event categories.