[documentation] Earlgrey software strap pins

### Description

The documentation isn't very clear about which pins are dedicated to software straps by the ROM - specifically there are pins to trigger bootstrapping and the RMA loop after reset.

The pinout table(s) mark the TAP and DFT strapping pins, but since the mask ROM is pseudo-hardware I think we should add the software straps here as well:

https://opentitan.org/book/hw/top_earlgrey/ip_autogen/pinmux/doc/pinout_asic.html

Start with the linked Earlgrey pinout table and review its existing TAP and DFT strap entries alongside the mask ROM context. Identify the pins used for bootstrapping and the RMA loop after reset, then update the pinout documentation so these software straps are listed clearly.

Written by the indexing model from the issue text.