docs: Add descriptions to many effects

[z5tm]

Description

Describe the changes

Added extra information to:

• SeveredHands (spawns hands that drop to the floor)
• CardiacArrest (8dmg/s + inital 16dmg for first second)
• AntiScp207 (AHP + wording)
• Scanned (Mutes the soundtrack)
• SilentWalk (10% reduction per intensity level)
• FogControl (wording)

Removed outdated information from:

• Ghostly ("Makes the player nearly invisible")

Added a description to:

• Slowness (1% less walk speed per intensity level)
• Scp1344 (Allows the player to see through walls, between spurts of visibility)
• SeveredEyes (doesn't blind the player, spawns eyeballs that drop to the floor, deals 10 damage per second)
• PitDeath (immediate death, included death reason + console death reason)
• Blurred (blurs the player's vision)
• Scp1576 (allows the affected player to speak with players in spectator/overwatch)
• Lightweight (Increases the player's jump height)
• HeavyFooted (Decreases the player's jump height)
• Fade (makes the user transparent, 255 being completely transparent)
• NightVision (allows the user to see in dark areas, does not extend viewing range, scales with intensity)
• Scp1509Resurrected (25 ahp, 75 max hp, doesn't overwrite hp if under 75 hp, clearing effect does not reset max hp nor ahp)
• AnomalousRegeneration (regardless of intensity, immediately sets the affect player's HS to maximum)
• AnomalousTarget (allows SCPs to see the target from a close distance, works on scps too)

Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
No.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentations

Submission checklist

• I have checked the project can be compiled
• I have tested my changes and it worked as expected

Other

• Still requires more testing

[Someone-193]

Seems legit

[VALERA771]

Daaaaaamn