Removed TRPL abbreviation which was not defined. Changed "version" to "edition" to keep consistency. Broke two complex sentences down into multiple simpler sentences.
https://doc.rust-lang.org/ links to https://doc.rust-lang.org/book/. From there, most people looking for the book’s content likely want to find the link to the second edition. This is hopefully more obvious than "read here" at the end of a paragraph.
* Remove warning about draft from second edition
* Add warning about first edition draft being older
* Change overview page to better state today's situation
