updated "How to scan" in this Doc

[RituRajSingh878]

I have improved how to scan a file in this doc as it is using an old format of example and if we will use it. It will show an error.

eg. ./scancode --format json samples samples.json

[AyanSinhaMahapatra]

Hi, @RituRajSingh878 you need to signoff your commit like here.

[AyanSinhaMahapatra]

@MaJuRG The link-check gives an error at "/docs/source/scancode-workbench/basics/building.rst"
"broken link: https://nodejs.org/en/" though that file wasn't changed in this commit. The same passes in previous builds of both my forked repo and of this repo through Travis-CI. What's happening here?

[steven-esser]

Probably just some networking hiccup on the TravisCI side.

When the original author adds his sign off and re-bases, this will probably pass.

[RituRajSingh878]

I tried to sign-off but due to some internal problem, I have to start from a new pull request.