Update Site Cleanup Guidelines

[tomojira]

• For distinguishing games with the same title on the same system, clarified that the year of release can also be used sometimes, not only the publisher or developer
• Removed excessive spaces in one line
• Clarified some other hub types that require at least 3 games - Hacks, Series Hacks, Fangames, and Unlicensed series
• Updated information on Hacks and Series Hacks hubs, since they're back to the old way of handling them - games can always be added to Series Hacks hubs even if they're already in a Hacks hub, and games without a Hacks hub should always be added to Uncategorized Hacks
• Removed outdated information on the AVGN and GameCenter CX hubs