Oauth2 scope management document sample curl request should be updated

[nilasini]

Description:
In [1] the sample curl request doesn't contain actual sample values but the yaml file in [1] contains a sample curl request. Need to update the doc [1] to contain the sample request.

[1] https://is.docs.wso2.com/en/5.11.0/develop/oauth2-scope-management-rest-apis/