Renamed "Tap_Center_r8.stl" to "[a]_Tap_Center_r8.stl" and "Tap_Belt_Cover_r8_x2.stl" to "[a]_Tap_Belt_Cover_r8_x2.stl"

[blownupp]

Keeping in line with prior releases and standard Voron printed part naming conventions, the following two STLs were renamed:

• "Tap_Center_r8.stl" to "[a]_Tap_Center_r8.stl"
• "Tap_Belt_Cover_r8_x2.stl" to "[a]_Tap_Belt_Cover_r8_x2.stl"