[ruby/optparse] More on tutorial (https://github.com/ruby/optparse/pull/23)

- Removed a largish block of repeated text.
- Added sections "Top List and Base List" and "Methods for Defining Options" (on, define, etc.).
- Linked from class OptionParser doc to the tutorial.

7f3195b9db

doc/optparse/ruby/basic.rb

@@ -12,5 +12,6 @@ end
 parser.on('-z', 'Whether to Z') do |value|
   p ['z', value]
 end
-# Parse the command line.
-parser.parse!
+# Parse the command line and return pared-down ARGV.
+p parser.parse!
+