Update CORS policy documentation for headers

For allowed-headers and expose-headers elements - Added the statement :The value * indicates all headers.

Author: PoojithaJujjavarapu

articles/api-management/cors-policy.md

@@ -80,13 +80,13 @@ The `cors` policy adds cross-origin resource sharing (CORS) support to an operat
 
 |Name|Description|Required|Default|
 |----------|-----------------|--------------|-------------|
-|header|Specifies a header name.|At least one `header` element is required in `allowed-headers` if that section is present.|N/A|
+|header|Specifies a header name.|At least one `header` element is required in `allowed-headers` if that section is present.|N/A|The value * indicates all headers.
 
 ### expose-headers elements
 
 |Name|Description|Required|Default|
 |----------|-----------------|--------------|-------------|
-|header|Specifies a header name.|At least one `header` element is required in `expose-headers` if that section is present.|N/A|
+|header|Specifies a header name.|At least one `header` element is required in `expose-headers` if that section is present.|N/A|The value * indicates all headers.
 
 ## Usage