Fast example should comes first [ci skip]

Author: JuanitoFatas

README.md

@@ -295,15 +295,15 @@ $ ruby -v code/enumerable/each_with_index-vs-while-loop.rb
 ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14]
 
 Calculating -------------------------------------
-     each_with_index    13.138k i/100ms
-          While Loop    23.385k i/100ms
+          While Loop    22.553k i/100ms
+     each_with_index    11.963k i/100ms
 -------------------------------------------------
-     each_with_index    140.303k (± 5.3%) i/s -    709.452k
-          While Loop    276.221k (± 5.3%) i/s -      1.380M
+          While Loop    240.752k (± 7.1%) i/s -      1.218M
+     each_with_index    126.753k (± 5.9%) i/s -    634.039k
 
 Comparison:
-          While Loop:   276221.4 i/s
-     each_with_index:   140302.7 i/s - 1.97x slower
+          While Loop:   240752.1 i/s
+     each_with_index:   126753.4 i/s - 1.90x slower
 ```
 
 ##### `Enumerable#map`...`Array#flatten` vs `Enumerable#flat_map` [code](code/enumerable/map-flatten-vs-flat_map.rb)