Update README to remove issue labels

This system wasn't as useful as I'd hoped.

README.md

@@ -45,35 +45,22 @@ $ mdbook test
 ## Contributing
 
 I’m not going to be accepting major changes at first, but pull requests to fix
-typos and such are welcome. Please file any issues for any bugs you find, and
-utilize the issue tagged with `Discussion` to raise any larger questions /
-feedback.
+typos and such are welcome. Please file any issues for any bugs you find.
 
 This repository is under the same license as Rust itself, MIT/Apache2.
 
 There are a number of labels on Issues:
 
-* `Discussion` issues are for discussing the chapters. There’s an issue per
-  section.
+* `Enhancement` issues are a request for an improvement of some kind.
 * `Bug` issues indicate problems in the text.
 * `Needs Backport` will be used when we are further along. At some point, we
   will import the text into their review system, and so changes made here will
   need to be upstreamed. This will track those.
 
-Finally, there’s the `S-` labels, which are for various ‘status’es:
-
-* `S-initial`: Steve has not done any work here yet.
-* `S-rough-draft`: Steve has worked up a rough draft of what this section will
-  look like.
-* `S-under-review`: Aaron and Steve are in the process of reviewing this
-  section.
-* `S-done`: imported into No Starch’s system. There may still be changes based
-  on their feedback, even after a section is marked `S-done`.
-
 ## No Starch
 
 As the book will be published by No Starch, we first iterate here, then ship the
 text off to No Starch. Then they do editing, and we fold it back in.
 
-As such, there’s a directory, `nostarch`, which corresponds to the `S-done`,
-and its current status in No Starch’s system.
+As such, there’s a directory, `nostarch`, which corresponds to the text in No
+Starch’s system.