Update 002-why-are-my-email-not-being-sent.md

[mattlamb99]

Included Gmail SMTP Specific help regarding the EHLO localhost issue referenced here : https://community.passbolt.com/t/email-not-working-smtp-relay-gmail/3281

[CLAassistant]

All committers have signed the CLA.

[AnatomicJC]

Thanks for your PR, we have integrated it with some refactor: https://help.passbolt.com/faq/hosting/why-email-not-sent#reason-5-gmail-smtp-relay-not-accepting-localhost-as-ehlo

Cheers,