add link to the relevant eslint rule

Author: bgits

README.md

@@ -1291,6 +1291,8 @@ Other Style Guides
 
   - [15.5](#15.5) <a name='15.5'></a> Ternaries should not be nested and generally be single line expressions.
  
+    eslint rules: [`no-nested-ternary`](http://eslint.org/docs/rules/no-nested-ternary.html).
+    
     ```javascript
     //bad
     const foo = maybe1 > maybe2