Remove `src/license.txt`
Remove `src/license.txt`

The `src/license.txt` file is not needed, plus, its presence
doesn't bring any value,

Ref: h5bp/html5-boilerplate#1655

rajat85/html5boilerplate.com,roblarsen/html5boilerplate.com,youprofit/html5boilerplate.com,youprofit/html5boilerplate.com,AndrewT51/html5boilerplate.com,h5bp/html5boilerplate.com,AndrewT51/html5boilerplate.com,h5bp/html5boilerplate.com,roblarsen/html5boilerplate.com,rajat85/html5boilerplate.com