Add Defaulting To Frozen String Literals as a ruby til

Author: jbranchaud

README.md

@@ -209,6 +209,7 @@ _305 TILs and counting..._
 - [Comparing Arrays In RSpec](ruby/comparing-arrays-in-rspec.md)
 - [Construct A Constant From A String](ruby/construct-a-constant-from-a-string.md)
 - [Create an Array of Stringed Numbers](ruby/create-an-array-of-stringed-numbers.md)
+- [Defaulting To Frozen String Literals](ruby/defaulting-to-frozen-string-literals.md)
 - [Destructuring Arrays In Blocks](ruby/destructuring-arrays-in-blocks.md)
 - [Disassemble Some Codes](ruby/disassemble-some-codes.md)
 - [Double Splat To Merge Hashes](ruby/double-splat-to-merge-hashes.md)

ruby/defaulting-to-frozen-string-literals.md

@@ -0,0 +1,19 @@
+# Defaulting To Frozen String Literals
+
+> The cold never bothered me anyway.
+
+The release of Ruby 2.2 introduced the ability to freeze string literals,
+making them immutable. With the release of Ruby 2.3, strings can be frozen
+by default without the use of `#freeze`. By adding the following magic
+comment at the top of a file
+
+```ruby
+# frozen_string_literal: true
+```
+
+all string literals will default to frozen. That means that all string
+literals in that file are immutable, cannot be modified. This gives the Ruby
+interpreter some performance gains due to reduced object allocation.
+
+This is the [issue](https://bugs.ruby-lang.org/issues/11473) that introduced
+it.