Add more guidance for new users

[ivankozik]

A little bit of help could mention:

• How to write a good, precise, easy-to-judge prediction
• Why people make personal predictions (more short-term predictions = faster to calibrate). Personal predictions are bewildering some new users.
• How to multiply probabilities, add independent probabilities, do a Bayesian update
• Links to LW articles about PredictionBook
• Other relevant links to LW
• Links to info about conjunction fallacy
• How to think through many future possibilities; perhaps some internal dialogue from a predictor could be written down.