boards/k210/maix-bit: Fix a typo in README
NOTE: To run nuttx for kostest, gdb needs to be used to load both nuttx_user.elf and nuttx
$ qemu-system-riscv64 -nographic -machine sifive_u -s -S
- $ riscv64-unknown-elf-gdb -ex 'target extended-remot:1234' -ex 'load nuttx_user.elf' -ex 'load nuttx' -ex 'c'
+ $ riscv64-unknown-elf-gdb -ex 'target extended-remote:1234' -ex 'load nuttx_user.elf' -ex 'load nuttx' -ex 'c'
6. TODO
