Fix license key docs for maxscale

Some notes of what to fix
1) ”Install MaxScale before adding the key — the configuration file you edit is created by the package. See the MaxScale Installation Guide.”
supposed to be a 3rd bullet?
feels funny how its written now

2) step 3 of license key
#3 Select the MaxScale card and follow the on-screen instructions to generate your key.

the enterprise one should say enterprise platform, its one key for all products (only maxscale is implementing it atm, more to come)

3) section "How MaxScale validates the key"
we dont need to share how the key actually works

4) we do need a section disclosing telemetry and the data thats being shared when feedback_enabled=true

5) for errors "Expiry and renewal"
just mention errors and level in relation to contract end, no mention of grace period

6) update section Troubleshoot with known error messages from code base