Improve docs for lass-body and lasso-head tags

[kristianmandrup]

It took us a long time, most of a day trying different strategies before we figured out that we had to use lass-body and lasso-head tags for lasso to work. We thought the head and body parts would have a sensible default insertion strategy if not present. The docs for these tags were hidden deep inside the long lasso docs. Better to mention them the first time they are required for others not to waste so many hours searching for that missing piece to make lasso shine.

Also pretty hard to understand the lasso- config.js file, what the difference is between using require: and not, when to use it etc. Please read through and update README docs to make it easier on newbies... Cheers!

[patrick-steele-idem]

Thanks for the feedback @kristianmandrup. I will try to improve the docs based on your feedback. If you also want to submit a PR to improve the docs then that would be greatly appreciated as well. It's not always obvious to me what is hard to understand since I'm very much used to the code so it very helpful to get outside contributions.

Thanks again.