Fixed a typo on the word 'include' in the default podspec documentation.

lib/cocoapods/command/spec.rb

@@ -518,7 +518,7 @@ Pod::Spec.new do |s|
 
   # ――― Source Code ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――― #
   #
-  #  CocoaPods is smart about how it include source code, for source files
+  #  CocoaPods is smart about how it includes source code, for source files
   #  giving a folder will include any h, m, mm, c & cpp files. For header
   #  files it will include any header in the folder.
   #  Not including the public_header_files will make all headers public.