Add info about modules in Go

[tisnik]

Add info about modules in Go

[vedprakashnautiyal]

I would like to work on this issue, but first can you tell me where exactly do we have to add this info

[satyampsoni]

Could you please explain what are you trying to say and if possible also add the references

[tisnik]

@vedprakashnautiyal it can be probably added as a new lesson (i.e. whole new set of slides)