Adding google tag manager

[jomsie]

• include js for google tag manager
• add classes on links for tracking

196

[YoussB]

I think we can merge this and deploy now. The rationale here being that we want to start collecting actual data and this code is not expected to change much, while the gtm part is the one that might change.

wdyt @jomsie ?

[jomsie]

@YoussB seems like a good plan to me, we can iterate on the data visualization and kinda progress with the things we wanna keep track of

[jomsie]

I'll just go ahead and merge, start getting data!