docs: kata description

Author: ParanoidUser

kata/5-kyu/index.md

@@ -38,6 +38,7 @@
 - [Pick peaks](pick-peaks "5279f6fe5ab7f447890006a7")
 - [Primes in numbers](primes-in-numbers "54d512e62a5e54c96200019e")
 - [Product of consecutive Fib numbers](product-of-consecutive-fib-numbers "5541f58a944b85ce6d00006a")
+- [Regex Password Validation](regex-password-validation "52e1476c8147a7547a000811")
 - [RGB To Hex Conversion](rgb-to-hex-conversion "513e08acc600c94f01000001")
 - [Rot13](rot13-1 "530e15517bc88ac656000716")
 - [ROT13](rot13 "52223df9e8f98c7aa7000062")

kata/5-kyu/regex-password-validation/README.md

@@ -0,0 +1,9 @@
+# [Regex Password Validation](https://www.codewars.com/kata/regex-password-validation "https://www.codewars.com/kata/52e1476c8147a7547a000811")
+
+You need to write regex that will validate a password to make sure it meets the following criteria:
+
+* At least six characters long
+* contains a lowercase letter
+* contains an uppercase letter
+* contains a digit
+* only contains alphanumeric characters (note that `'_'` is not alphanumeric)