Add Or Operator Precedence as a ruby til

ruby/or-operator-precedence.md

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+# Or Operator Precedence
+
+What's the difference between `||` and `or` in Ruby?
+
+Let's look at an example to find out. First, let's start with some boolean
+variables:
+
+```ruby
+> a, b = false, true
+=> [false, true]
+```
+
+Now, let's try the different _or_ operators:
+
+```ruby
+> a || b
+=> true
+> a or b
+=> true
+```
+
+Cool, they seem to work as expected.
+
+Finally, let's capture the result in a variable:
+
+```ruby
+> c = a or b
+=> true
+> c
+=> false
+```
+
+But why is `c` false and not true? Operator precedence. The assignment
+operator (`=`) takes precedence over the `or` operator causing `c` to be
+assigned to the value of `a` (`false`) before `or`'d with `b`.
+
+[source](http://stackoverflow.com/questions/2083112/difference-between-or-and-in-ruby)