New README.md

@seriousamlqz, @yzhang90, @grosu Please review

@grosu, please assign someone who knows better than me to write the Static Weaving Section: I don't use that option.
@grosu, I like your feature request :) I opened a new issue for it [here](https://github.com/runtimeverification/javamop/issues/92). Please check whether I captured your intent correctly and comment directly on the issue itself.

This feature that you requested is so close to what ```-usedb``` does, it makes me wonder whether your original confusion resulted from my poor choice of name for the option. Any ideas from everyone (@yzhang90, @seriousamlqz, @xiaohe27)  for a better name?

Lastly, I had explained what ```-usedb``` does prior to your last comment, and I massaged it even more now, based on your comments. Let me know whether you have any more comments.