Update README.md
Update README.md
Update README.md
Update README.md

We have to enter the cloned directory in order to compile this.
Merge pull request #41 from bbs4us/patch-1

Update README.md
Update README.md

In case that git wasn't installed
Merge pull request #43 from bbs4us/patch-2

Update README.md
Add license tag with SPDX identifiers
referer https://dev.openwrt.org/changeset/43155/
Merge pull request #45 from cj1324/add_license_tag

Add license tag with SPDX identifiers
Automatically get effective interface name

Some people don't know to modify the script.