[docs] Inaccurate commands in README.md

[qiaojingx]

Description

Inaccurate commands in README.md

Test Code

README.md

Steps to Reproduction

1. Follow the introduction FRDM-K64F Platform
   Try to build the Zephyr OS hello_world sample to narrow down the problem:
   

2. Follow the introduction Networking with QEMU to setup net-tools
   Terminal 1:
   sudo ./net-tools/loop-socat.sh
   Terminal 2:
   ./net-tools/loop-slip-tap.sh

Actual Result

1. bash: cd: deps/zephyr/samples/hello_world/nanokernel: No such file or directory

Expected Result

1. The path should be cd deps/zephyr/samples/hello_world
2. Terminal 1:
   ./loop-socat.sh
   Terminal 2:
   sudo ./loop-slip-tap.sh

Test Builds

Branch	Commit Id	Test Date	Result
master	1e9da6f	Apr 11, 2017	Fail
zjs-0.3	f8f9621	Apr 11, 2017	Fail

Additional Information

[qiaojingx]

@jprestwo K64 build instruction has been updated in commit 2487b22. But the instruction of Networking with QEMU is still not inaccurate. Please find current behavior from the picture in description. I think it is better to update as below(keep consistent with https://www.zephyrproject.org/doc/subsystems/networking/qemu_setup.html):
Terminal 1:
./loop-socat.sh
Terminal 2:
sudo ./loop-slip-tap.sh

[cuiyanx]

Sync 0.3 docs fix and sample added: #1036

[qiaojingx]

Verified with commit 46c8cc2 in zjs-0.3 branch. K64 build instructions have been fixed. Other instructions are the same as master.