Review mentor and mentee guides

[khairahscorner]

We need to review and update the mentor and mentee pocket guides to:

• use WCC branding colours, fonts, etc (check Branding folder)
• update WomenWhoCode to WCC anywhere necessary
• propose and add anything else we should consider e.g clear warnings about breach of rules, communication, etc

Mentee guide v1: https://drive.google.com/file/d/1xPbW8BlQoLXkuAJ7m0RuvOV02Opyr445/view?usp=sharing
Mentor guide v2: https://drive.google.com/file/d/1wTkCSG95BVg-0XX4r7FnFiV24_SXlbM_/view?usp=sharing