How to export the XML file that `ghidra2stubs` expects from Ghidra?

[Asmageddon]

I managed to import the function names from stubs.S into Ghidra, as well as disassemble and name some extra functions.

I'd like to export and generate a new stubs file, but I have no idea how to generate the stm32.bin.xml file containing the symbols.

[Asmageddon]

Also just like last time, pinging @osresearch, @wormyrocks, @colinoflynn :P