Rewording the `Client_Credential` area to clarify that you're still passing `password` in the JSON.  Fixed Typos regarding OAuth tutorial.
Rewording the `Client_Credential` area to clarify that you're still passing `password` in the JSON.  Fixed Typos regarding OAuth tutorial.

poisa/apigility-documentation,santiph/apigility-documentation,PowerKiKi/apigility-documentation