Remove duplicate section "pad-string-interpolation" (rubocop#568)

Author: Sou.K

README.md

@@ -3310,11 +3310,11 @@ resource cleanup when possible.
 
   ```Ruby
   timestamp = Time.now.to_i
-  
+
   # bad
   timestamp.is_a? Fixnum
   timestamp.is_a? Bignum
-  
+
   # good
   timestamp.is_a? Integer
   ```
@@ -3337,18 +3337,6 @@ resource cleanup when possible.
   email_with_name = format('%s <%s>', user.name, user.email)
   ```
 
-* <a name="pad-string-interpolation"></a>
-  With interpolated expressions, there should be no padded-spacing inside the braces.
-<sup>[[link](#pad-string-interpolation)]</sup>
-
-  ```Ruby
-  # bad
-  "From: #{ user.first_name }, #{ user.last_name }"
-
-  # good
-  "From: #{user.first_name}, #{user.last_name}"
-  ```
-
 * <a name="consistent-string-literals"></a>
   Adopt a consistent string literal quoting style. There are two popular
   styles in the Ruby community, both of which are considered good - single