Integer is class in Ruby

- Also fixes trailing white space in hints file.

exercises/concept/chess-game/.docs/hints.md

@@ -3,14 +3,14 @@
 ## 1. Define rank & file range
 
 - You need to define two [constant][constants] that should hold a [`Range`][range] of ranks and files.
-- The ranks should be an [`Int`][integers] `range` from 1 to 8.
+- The ranks should be an [`Integer`][integers] `range` from 1 to 8.
 - The files should be a [`String`][string] `Range` from 'A' to 'H'.
 - The constant needs to be defined in the `Chess` [module][module].
 
 ## 2. Check if square is valid
 
 - You need to check if a value is within a range.
-- There is [a method][include] that can be used to check if a value is within a range. 
+- There is [a method][include] that can be used to check if a value is within a range.
 
 ## 3. Get player's nickname
 

exercises/concept/chess-game/.docs/instructions.md

@@ -31,7 +31,7 @@ Chess::Files
 The game will have to check if a square is valid.
 A square is valid if the rank and file are within the ranges of the ranks and files.
 
-Define the `Chess.valid_square?` method that takes the arguments `rank` that holds an int of the rank and `file` that holds a char of the file.
+Define the `Chess.valid_square?` method that takes the arguments `rank` that holds an integer of the rank and `file` that holds a char of the file.
 The method should return `true` if the rank and file are within the ranges of the ranks and files and return `false` otherwise.
 
 ```ruby

exercises/concept/chess-game/.docs/introduction.md

@@ -1,7 +1,7 @@
 # Ranges
 
 [Ranges][range] represent an interval between two values.
-The most common types that support ranges are `Int` and `String`.
+The most common types that support ranges are `Integer` and `String`.
 They can be used for many things like quickly creating a collection, slicing strings, checking if a value is in a range, and iteration.
 They are created using the range operator `..` or `...` (inclusive and exclusive, respectively).