Add missing vbat identifier on right joy-con PCB

On the right joy-con image found in joycon_pcb.pdf, the vbat is unidentified as opposed to what can be found for the left joy-con.

According to this post https://www.reddit.com/r/SwitchPirates/comments/12blymz/finding_a_schematic_diagram_for_right_joycon/, the vbat is under JC9, left to JC6.

This picture can be used as reference: https://i.ibb.co/Nj3kgqz/Screenshot-20230404-235122-2.png