fix &. description

Author: IlyaUmanets

refactorings/conditionals_when_object_is_nil.md

@@ -11,11 +11,13 @@ event.end_date.nil? ? '' : event.end_date.to_s(:long)
 ```ruby
 event.end_date.try(:to_s, :long)
 ```
-**Or:**
+
+**Or (2.3+):**
 
 ```ruby
 event.end_date&.to_s&.long
 ```
+[About &. operator](http://mitrev.net/ruby/2015/11/13/the-operator-in-ruby/)
 
 **Remembering:** [try](http://apidock.com/rails/Object/try) is a Rails method and it's not in Ruby Core.
 

tricks/source_code/splat_operator.rb

@@ -5,6 +5,8 @@
 arguments = [1, 2, 3, 4]
 my_method(*arguments) # any number of arguments
 
+
+
 # or:
 
 arguments = [2, 3, 4]
@@ -15,6 +17,7 @@
 arguments = [1, 2]
 my_method(*arguments, 3, 4) # any number of preceding arguments
 
+
 # or:
 
 arguments = [2, 3]