ruby: 0003-methods.rb: added destructive and non-destructive demo
ruby: 0003-methods.rb: added destructive and non-destructive demo

This patch is created to add demo describing descructive and
non-destructive method.

Signed-off-by: (Holloway) Chew, Kean Ho <bbd8faa40b0f348214bf4124b281a301299ba6dd@gmail.com>

josiahsoh/learning,hollowaykeanho/learning,hollowaykeanho/learning,hollowaykeanho/learning,josiahsoh/learning,josiahsoh/learning,josiahsoh/learning,hollowaykeanho/learning,hollowaykeanho/learning,josiahsoh/learning