Update README.md

Author: ikostan

kyu_6/README.md

@@ -39,7 +39,7 @@ rank - the harder the kata the faster you advance.
 | 20  | [Help the bookseller !](https://www.codewars.com/kata/54dc6f5a224c26032800005c)                                |           [Solution](https://github.com/ikostan/codewars/tree/master/kyu_6/help_the_bookseller)            |
 | 21  | [Character with longest consecutive repetition](https://www.codewars.com/kata/586d6cefbcc21eed7a001155)        |            [Solution](https://github.com/ikostan/codewars/tree/master/kyu_6/longest_repetition)            |
 | 22  | [Multiples of 3 or 5](https://www.codewars.com/kata/514b92a657cdc65150000006)                                  |           [Solution](https://github.com/ikostan/codewars/tree/master/kyu_6/multiples_of_3_or_5)            |
-| 23  | [No arithmetic progressions](https://www.codewars.com/kata/5e0607115654a900140b3ce3)                           |                                         [Solution not available]()                                         |
+| 23  | [No arithmetic progressions](https://www.codewars.com/kata/5e0607115654a900140b3ce3)                           |             [Solution not available](https://github.com/iKostanOrg/codewars/tree/master/kyu_6)             |
 | 24  | [Number Zoo Patrol](https://www.codewars.com/kata/5276c18121e20900c0000235)                                    |            [Solution](https://github.com/ikostan/codewars/tree/master/kyu_6/number_zoo_patrol)             |
 | 25  | [Numericals of a String](https://www.codewars.com/kata/5b4070144d7d8bbfe7000001)                               |           [Solution](https://github.com/ikostan/codewars/tree/master/kyu_6/numericals_of_string)           |
 | 26  | [Permute a Palindrome](https://www.codewars.com/kata/58ae6ae22c3aaafc58000079)                                 |           [Solution](https://github.com/ikostan/codewars/tree/master/kyu_6/permute_a_palindrome)           |