doc: add missing target types

doc: add missing target types

missing target types are arm946e, avr32_ap7k, cortex_r4, dsp5680xx,
hla_target, mips_mips64, nds32_v2, nds32_v3, nds32_v3m, quark_d20xx,
quark_x10xx, riscv, stm8 and testee

Change-Id: I38f6ed78ee88c09add4b779cd409ebb1e219304f
Signed-off-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-on: http://openocd.zylin.com/5487
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins
Reviewed-by: Tim Newsome <tim@casualhacker.net>
Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>