Admin add comment on a transaction

This api is for Admin to add comment on a transaction

REST

Fields	Type	Description	Example	O/M
URL	string		`/v1/comp_emp_txns/<txn_id>/comments/`	M
METHOD	string		POST	M
content-type	string	JSON	application/json	M
x-access-token	string	Session token with validity	token	M

{
        "comment":"reviewer comments"
}