Merge pull request #3913 from singjsong/ruby-block-syntax

[ruby/en] Add Ruby shorthand block syntax examples

ruby.html.markdown

@@ -430,6 +430,16 @@ def guests(*array)
   array.each { |guest| puts guest }
 end
 
+# There is also the shorthand block syntax. It's most useful when you need
+# to call a simple method on all array items.
+upcased = ['Watch', 'these', 'words', 'get', 'upcased'].map(&:upcase)
+puts upcased
+#=> ["WATCH", "THESE", "WORDS", "GET", "UPCASED"]
+ 
+sum = [1, 2, 3, 4, 5].reduce(&:+)
+puts sum
+#=> 15
+
 # Destructuring
 
 # Ruby will automatically destructure arrays on assignment to multiple variables.