Minor update - in-game hints

After giving the game to some friends to play, I've realized that game tells player close to nothing about how to play or what's going on. Hence I've added several hints:

• Controls and general game goal on starting room
• Note about time required to get keys and energy rewards
• Notifying player when entering reinforced room (so they can figure out what colored walls mean). Still might use some explanation on reinforcement system, but no idea where to put it, so I leave it out of jam version.

Now that's actually last update, I promise :D