Note from workshops before 2020

[stijnvanhoey]

I recovered still following todos:

• use "gender" instead of "sex"
• add visual schema for melt (https://twitter.com/justmarkham/status/1206950457677094913) + improve docs
• provide good cheatsheet for during the course

@jorisvandenbossche you can check jorisvandenbossche/DS-python-data-analysis#122 and jorisvandenbossche/DS-python-data-analysis#64 yourself to see if I'm missing still a remark to tackle.