Implement telemetry in MeiliSearch integrations about integration-guides

[eskombro]

I have read this issue, and it is a very interesting discussion but also could be a bit sensitive. I have to say that I struggle to find a clear position myself on if we should add this by default, or just make it possible to be activated, and ask politely the developers to activate it to helps the development process (which will of course create not-representative and not-reliable data, but coming from people who actively want to share it).

I am totally open to making this discussion evolve (as my point of view of course) :)

[curquiza]

We are going to start with using user-agent header and sending it to MeiliSearch server as suggested here: #58

This way:

• we can use the already implemented analytics in MeiliSearch, which is easier for a first MVP.
• if the users want to desable analytics, there is only one step to do (desable analytics for MeiliSearch)