[Docs] The info part of `AddActiveCharge` is wrong

EntityPlayer:AddActiveCharge()'s documentation mentions the following:

FlashHUD appears to be redundant. Chargebar flashes regardless of using true or false.

However, this is not true.
I've been making an active item that recharges over time but not with room clears, and ended up needing to implement my own clock using MC_POST_UPDATE.

When flashHUD is true, the game produces a sound effect on charge and the bar flickers.
When flashHUD is false, the charge is silent and there is no flicker.

https://github.com/user-attachments/assets/6dc51e32-30dd-4412-8ab3-1f8e23141216

Note that I also tried without the "Fancy Charge Bar" mod to make sure it was not involved in this and can confirm it wasn't.
Also due to file size restrictions the quality is mediocre and the flicker is barely very visible--but it is there!

I would open a PR but I'm not entirely sure how to reword it and would gladly do so with some advice. 😊

Start in docs/docs/EntityPlayer.md at the EntityPlayer:AddActiveCharge() entry. Update the FlashHUD description to state that true produces a charge sound and bar flicker, while false is silent and does not flicker; the documentation should no longer call the parameter redundant.