Document the risks of external contracts freezing the market

[QGarchery]

The external contracts are the tokens, the IRM, and the oracle. Each one could revert directly, or cause a revert, which would freeze (or partially freeze) the market. Those should be documented so that the market creator can avoid the issues, and so that the users can avoid more risky markets. The parameters should also be tweaked accordingly.

Here is the related notion page for this issue.

Left to do:

• review the notion page
  • make sure that there are not other risks
  • review the math
  • make sure that the values of the parameters match the expectation of the risks
• document those risks where appropriate