Update rollover new index operation request for serverless (#5189)

* add individual request examples for serverless and stack

* add empty value block to denote empty POST body for serverless request

Author: ketkee-aryamane

specification/indices/rollover/examples/request/indicesRolloverRequestExample1.yaml

@@ -1,6 +1,6 @@
-summary: Create a new index for a data stream.
+summary: Stack request
 method_request: POST my-data-stream/_rollover
-# description: ''
+description: 'Create a new index for a data stream'
 # type: request
 value: "{
 

specification/indices/rollover/examples/request/indicesRolloverRequestExample2.yaml

@@ -0,0 +1,4 @@
+summary: Serverless request
+method_request: POST my-data-stream/_rollover
+description: 'Create a new index for a data stream'
+value: '{}'