Update EntityPlayer.md with function description

Added description for CanAddCollectibleToInventory function.

Author: TiredFoks

docs/docs/EntityPlayer.md

@@ -172,6 +172,7 @@ Blocks the provided [CollectibleType](https://wofsauge.github.io/IsaacDocs/rep/e
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 ### CanAddCollectibleToInventory () {: aria-label='Functions' }
 #### boolean CanAddCollectibleToInventory ( [CollectibleType](https://wofsauge.github.io/IsaacDocs/rep/enums/CollectibleType.html) Collectible ) {: .copyable aria-label='Functions' }
+Used to determine which items can be added to Tainted Isaac's limited inventory.
 
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 ### CanCrushRocks () {: aria-label='Functions' }