x86 q35 machine type documentation is missing
Description of problem:
The x86 machine type of q35 was added in 2012 by commit
df2d8b3ed4d2 ("q35: Introduce q35 pc based chipset emulator")
but no documentation was added to docs/master/system/target-i386.html
Additional information:
There was development documentation at https://wiki.qemu.org/Features/Q35