Update using-vivado.md

quad/doc/using-vivado.md

@@ -9,6 +9,10 @@ This will launch vivado in gui mode. See the vivado documentation for other mode
 
 # Startup Scripts
 If you want to run any tcl scripts on startup, such as installing board backages
-place them in `/local/ucart/.Xilinx/Vivado/` They will be sourced on startup.
+source them in `/local/ucart/.Xilinx/Vivado/Vivado_init.tcl` This will run on startup.
+
+# Simulation
+[This ug](https://www.xilinx.com/support/documentation/sw_manuals/xilinx2018_1/ug937-vivado-design-suite-simulation-tutorial.pdf) has info on Vivado simulation (in batch mode too).
+This should be usable for automated regression tests.
 
 *This document will get updated as needed*
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