Define how partners should be ranked

We should document how partners are ranked, since up until now I was the one who assigned the rankings, and they were based on my own subjective criteria from quite a while ago.

My reasoning was that a higher number meant a higher priority:

• Tier 3: Critical infrastructure, or partners that covered multiple categories.
• Tier 2: Partners that provide an important service in a single category (e.g. ESP or Security).
• Tier 1: Partners that support non-critical infrastructure, such as downloads or content.

I don't think these criteria should just be based on my personal opinion, though. They should be documented and agreed upon by the people who oversee the project as a whole.

Non sono identificati file, test o punti di ingresso; inizia esaminando i criteri di Tier 1–3 proposti in questa Issue e la discussione dei responsabili del progetto. Il lavoro è completato quando i criteri di ranking sono stati concordati e documentati nella documentazione appropriata del progetto.