docs: slashing factors rounding

[0xClandestine]

Motivation:

Fixes an issue where rounding in slashingFactor calculations can result in a factor of zero, causing stakers to lose all their withdrawable shares under specific edge cases. This can be exploited by malicious operators through intentional self-slashing and small beacon chain penalties. (EGSL-16)

Modifications:

• Added documentation note informing users of the potential rounding issue with slashingFactor when operatorMaxMagnitude and beaconChainSlashingFactor are extremely small.
• Implemented frontend warnings for stakers when delegating to operators with extremely low maxMagnitude, helping mitigate potential exploits.

Result:

• Increased transparency on edge cases that could lead to loss of withdrawable shares.
• Preventative warnings to stakers to avoid delegation to potentially malicious or risky operators.