Merge pull request #20 from Eric-Guo/master

Add require rspec/matchers in readme.

README.md

@@ -81,17 +81,24 @@ nodes) should be ignored when comparing for equivalence.  Defaults to `nil`.  (U
 EquivalentXml includes a custom matcher for RSpec (version >=1.2.4) that makes including XML
 equivalencies in your spec tests a cinch!
 
+Add below two line to `spec_helper.rb`:
+
+```ruby
+require 'rspec/matchers' # req by equivalent-xml custom matcher `be_equivalent_to`
+require 'equivalent-xml'
+```
+
 Equivalency:
 
-    node_1.should be_equivalent_to(node_2)
-    node_1.should_not be_equivalent_to(node_2)
+    expect(node_1).to be_equivalent_to(node_2)
+    expect(node_1).not_to be_equivalent_to(node_2)
 
 Chained modifiers:
 
-    node_1.should be_equivalent_to(node_2).respecting_element_order
-    node_1.should be_equivalent_to(node_2).with_whitespace_intact
-    node_1.should be_equivalent_to(node_2).respecting_element_order.with_whitespace_intact
-    node_1.should be_equivalent_to(node_2).ignoring_content_of("SerialNumber")
+    expect(node_1).to be_equivalent_to(node_2).respecting_element_order
+    expect(node_1).to be_equivalent_to(node_2).with_whitespace_intact
+    expect(node_1).to be_equivalent_to(node_2).respecting_element_order.with_whitespace_intact
+    expect(node_1).to be_equivalent_to(node_2).ignoring_content_of("SerialNumber")
 
 ## Contributing to equivalent-xml