Collect the browser language

[angaither]

Browser language should be available in fastly, we should store this

Related:

• user_language in Message Broker request: Transactional Payload Update #437

[DFurnes]

This shouldn't be too hard to do, we just need to know what header this will be provided in from Fastly.

@blisteringherb Going to assign you for the time being. Let me know when you know what header this will be sent through and I'll hook things up on our end!

[DFurnes]

@angaither @mshmsh5000 Are we still interested in doing this?

[angaither]

I think, yes, the more info we have about our users will always be helpful.
@blisteringherb if you have time to do this, it would be great.