Merge pull request #284 from jrvidal/clarification-1.30

Small wording correction

Author: steveklabnik

_posts/2018-10-25-Rust-1.30.0.md

@@ -43,7 +43,7 @@ struct Pet {
 And convert a `Pet` to and from JSON using `serde_json` because `serde_derive`
 defined `Serialize` and `Deserialize` in a procedural macro.
 
-Rust expands on this by adding the ability to define two other kinds of
+Rust 1.30 expands on this by adding the ability to define two other kinds of
 advanced macros, "attribute-like procedural macros" and "function-like
 procedural macros."