Update guideline to be more expressive

Author: teoljungberg

style/ruby/README.md

@@ -11,7 +11,8 @@ Ruby
 * Avoid explicit return statements.
 * Avoid using semicolons.
 * Avoid bang (!) method names. Prefer descriptive names.
-* Avoid `class A::B`, [Example][class definition example]
+* Avoid defining classes and modules using shorthand nesting (class A::B)
+  [Example][class definition example]
 * Don't use `self` explicitly anywhere except class methods (`def self.method`)
   and assignments (`self.attribute =`).
 * Prefer `detect` over `find`.