Grindstones attached to bookshelfs reduces the minimum enchantment level requirement

When creating a level 30 enchantment table setup, you can reduce the required level needed for enchanting an item.

Steps To Reproduce: Place grindstones sideways on the two bottom bookshelves facing the enchantment table.

Actual Result: The minimum enchantment level requirements are reduced

Expected Result: Minimum level requirements should be unaffected.

Note: This only reduces the required level needed for an enchantment, not the cost!

Example: If a Level III enchant requires 30 levels, performing this exploit may reduce the level threshold down to 22 required levels (The Level III enchant will still cost 3 levels.)