Events should have `tags` to help group related events together

[karthikb351]

This is a better way to cross-sell/promote events together automatically.

[mediatinker]

Let's list out some of the proposed tags and see what we get. Could be a general or a granular list. Here are a few to start:

data science
big data
machine learning
deep learning
artificial intelligence
design
content management
UI/UX
health
wellness
habit
weight loss
fitness
javascript
mobile
android

[karthikb351]

@mediatinker Moving this discussion to #141 - where we can actually list them out.