Documentation updates & fixes

I found the documentation confusing. Similar class names were used in some places and not others. There was a section where pikabu was attached to a jQuery/Zepto object, but no documentation how how that worked or what it did?

After getting Zepto working, I updated the readme.md with the content that I would have preferred to see.

BTW, if $('.my-object').zepto({ .. options .. }); does work, please reincorporate it into the documentation.