fix[event.schema.json]: remove click_through

[AnkitSiva]

This is a minor change. I think we should remove the enum value click_through as that indicates a subset of click and has specific connotations in advertising.

[jzonthemtn]

I agree - a click through is just a click.

[miike]

Agreed - I'd consider adding "impression" to the enum to make it a bit more clear on how clickthrough rate could be calculated.

[jzonthemtn]

@miike That might be the purpose of view. Perhaps impression is a better term than view.

[miike]

I think depending on the vertical they might mean distinct things (e.g., for ecommerce a page view of the PDP page would be a view versus a tile impression in search results). It's probably not particularly important but just depends on how opinionated you want the enum to be.

[epugh]

@miike would you be interested in submitting impression as it's own PR? It's far enough from click_through that it seems odd to have it be part of this PR, and it does seem like a valid question on it's own....!

[miike]

Sure thing - I've done that in #22

[epugh]

I am going to leave this one open a bit longer, and the reason is that the "specific connotations in advertising" is kind of what makes this potentially REALLY valuable. Those same connotations also apply to very common search use cases. I did a search and I am clicking through to this detail page....

I don't see merging this materially as making the 1.1 release worse, so I'd like to leave this open for more discussion and try and get it decided for 1.2.