3.0.0-preview2 added

[easy] promote 'rbenv install -L', an alias of '--list-all'

Support specifying the complete mirror URL

mark maglev as EoL

Bump openssl-1.1.1h from old versions

Add definition for Ruby 2.7.2

Ruby 2.7.2 has been released.
https://www.ruby-lang.org//en/news/2020/10/02/ruby-2-7-2-released/

Add definition for 3.0.0-preview1

As far as I search on Twitter, the short option is not well known.

Rename 2.8.0 to 3.0.0

  https://github.com/ruby/ruby/commit/21c62fb670

Add definition for mruby 2.1.2

Add definition for JRuby 9.2.13.0

JRuby 9.2.13.0 has been released.
https://www.jruby.org/2020/08/03/jruby-9-2-13-0

Rename CONDUCT.md to CODE_OF_CONDUCT.md

Conforms to github's conventional filename

* '+' needs to be considered part of the name for --definitions and -l
  to see truffleruby and truffleruby+graalvm as separate.

* Supports using other GraalVM languages such as JavaScript, Python, R and Java.
* Supports running TruffleRuby on JVM and not only Native.
* Add GraalVM 20.1.0.

Signed-off-by: Mingxiang Xue <mingxiangxue@gmail.com>

compatible with macOS 11

Add definition for JRuby 9.2.12.0