Missing parameter for audit log header

[danny-may]

A number of endpoints support the X-Audit-Log-Reason header, but this isnt included in the spec anywhere. I think that adding it to the parameters of all operations which support it would be helpful

{
    "name": "X-Audit-Log-Reason",
    "in": "header",
    "required": false,
    "schema": {
        "type": "string"
    }
}