Add the Limit Split til to the ruby directory.

ruby/limit-split.md

@@ -0,0 +1,37 @@
+# Limit Split
+
+I've only ever used Ruby's
+[`String#split`](http://ruby-doc.org//core-2.2.0/String.html#method-i-split)
+with the delimiter argument (e.g. `"this string has spaces".split(" ")`).
+This method has another argument that can be specified, the `limit`
+argument. With `limit`, you can *limit* the number of times that the split
+happens.
+
+```ruby
+"this string has many spaces".split(" ")
+# => ["this", "string", "has", "many", "spaces"]
+"this string has many spaces".split(" ", 3)
+# => ["this", "string", "has many spaces"]
+```
+
+There are surely many use cases, but one that stands out (from [The Rails 4
+Way](https://leanpub.com/tr4w)) is for splitting a name into *first* and
+*last* names.
+
+```ruby
+"Josh Branchaud".split(" ", 2)
+# => ["Josh", "Branchaud"]
+"David Heinemeier Hansson".split(" ", 2)
+# => ["David", "Heinemeier Hansson"]
+```
+
+This really simplifies the code that is needed to make the following example
+work:
+
+```ruby
+def create_user(name)
+  user = User.new
+  user.first_name, user.last_name = name.split(" ", 2)
+  user.save
+end
+```