Update README > Chapter 6

Author: lorensr

README.md

@@ -8,7 +8,7 @@ Branch `master` is deployed to [https://graphql.guide](https://graphql.guide), a
 
 ## Chapter 6
 
-Branches `0-18` have the most up-to-date versions of the code (often newer than the most recent published version of the ebook). When code has changed between book revisions, a new version is created, and each branch is tagged, with the naming format `[step]_[version]`. For instance, r1 of the book was published with version `0.1.0` of this repo, so the tag for step 5 was [`5_0.1.0`](https://github.com/GraphQLGuide/guide/releases/tag/5_0.1.0).
+Numbered branches (`0` and up) have the most up-to-date code (often newer than the most recent published revision of the book). When code has changed between book revisions, a new code version is created, and each branch is tagged, with the naming format `[step]_[version]`. For instance, r1 of the book was published with version `0.1.0` of this repo, so the tag for step 5 was [`5_0.1.0`](https://github.com/GraphQLGuide/guide/releases/tag/5_0.1.0).
 
 ## Contributors