Added README for day 5.

Author: danspencer

day05/README.md

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+# [Day 5: Doesn't He Have Intern-Elves For This?](http://adventofcode.com/day/5)
+
+## --- Part One ---
+
+Santa needs help figuring out which strings in his text file are naughty or nice.
+
+A __nice string__ is one with all of the following properties:
+
+- It contains at least three vowels (aeiou only), like aei, xazegov, or aeiouaeiouaeiou.
+- It contains at least one letter that appears twice in a row, like xx, abcdde (dd), or aabbccdd (aa, bb, cc, or dd).
+- It does __not__ contain the strings ab, cd, pq, or xy, even if they are part of one of the other requirements.
+
+For example:
+
+- ugknbfddgicrmopn is nice because it has at least three vowels (u...i...o...), a double letter (...dd...), and none of the disallowed substrings.
+- aaa is nice because it has at least three vowels and a double letter, even though the letters used by different rules overlap.
+- jchzalrnumimnmhp is naughty because it has no double letter.
+- haegwjzuvuyypxyu is naughty because it contains the string xy.
+- dvszwmarrgswjxmb is naughty because it contains only one vowel.
+
+How many strings are nice?
+
+Your puzzle answer was _236_.
+
+## --- Part Two ---
+
+Realizing the error of his ways, Santa has switched to a better model of determining whether a string is naughty or nice. None of the old rules apply, as they are all clearly ridiculous.
+
+Now, a nice string is one with all of the following properties:
+
+- It contains a pair of any two letters that appears at least twice in the string without overlapping, like xyxy (xy) or aabcdefgaa (aa), but not like aaa (aa, but it overlaps).
+- It contains at least one letter which repeats with exactly one letter between them, like xyx, abcdefeghi (efe), or even aaa.
+
+For example:
+
+- qjhvhtzxzqqjkmpb is nice because is has a pair that appears twice (qj) and a letter that repeats with exactly one letter between them (zxz).
+- xxyxx is nice because it has a pair that appears twice and a letter that repeats with one between, even though the letters used by each rule overlap.
+- uurcxstgmygtbstg is naughty because it has a pair (tg) but no repeat with a single letter between them.
+- ieodomkazucvgmuy is naughty because it has a repeating letter with one between (odo), but no pair that appears twice.
+
+How many strings are nice under these new rules?
+
+Your puzzle answer was _51_.