Address some docs, build.sbt, .gitmodules

docs/Prototyping/index.rst

@@ -3,7 +3,6 @@ Prototyping Flow
 
 Chipyard supports FPGA prototyping for local FPGAs supported by `fpga-shells <https://github.com/sifive/fpga-shells>`__.
 This includes popular FPGAs such as the Xilinx VCU118 and the Xilinx Arty 35T board.
-FPGA prototyping allows for orders-of-magnitude faster speeds than software RTL simulators at the cost of slower compile times and less design introspection.
 
 .. Note:: While ``fpga-shells`` provides harnesses for other FPGA development boards such as the Xilinx VC707 and some MicroSemi PolarFire, only harnesses for the Xilinx VCU118 and Xilinx Arty 35T boards are currently supported in Chipyard.
     However, the VCU118 and Arty 35T examples demonstrate how a user may implement support for other harnesses provided by fpga-shells.