Added github markdown-style README.
Added github markdown-style README.

jenkinsci/ivy-plugin,burghduffkc/ivy-plugin,arothian/ivy-plugin,burghduffkc/ivy-plugin,opencloud/ivy-plugin,arothian/ivy-plugin,anastasiyam/ivy-plugin,jenkinsci/ivy-plugin,anastasiyam/ivy-plugin,opencloud/ivy-plugin