Start the wording style chapter

This is just a stub, with the expectation that it will be
expanded/rewritten later.

Author: ehuss

contributor-guide/src/SUMMARY.md

@@ -17,7 +17,7 @@
 - [Rust grammar](grammar.md)
 - [Attributes](attributes.md)
 - [Style guide](style/index.md)
-    - [Wording]()
+    - [Wording](style/wording.md)
     - [Language and grammar]()
     - [Punctuation]()
 - [Review policy](review-policy.md)

contributor-guide/src/style/wording.md

@@ -0,0 +1,5 @@
+# Wording
+
+Use American English spelling.
+
+Avoid qualifying something as "in Rust"; the entire Reference is about Rust.

docs/authoring.md

@@ -8,10 +8,8 @@ This document serves as a guide for editors and reviewers. Some conventions and
 
 Idioms and styling:
 
-* Use American English spelling.
 * Use Oxford commas.
 * Avoid slashes for alternatives ("program/binary"); use conjunctions or rewrite it ("program or binary").
-* Avoid qualifying something as "in Rust"; the entire reference is about Rust.
 
 ## Content guidelines