impelementation of update command

[utam0k]

This issue creates an implementation that will serve as a template for now, and the other parameters that will be updated will be managed in a separate issue as a good first issue. ref: https://github.com/opencontainers/runc/blob/master/man/runc-update.8.md

[utam0k]

@fbrv It's a little more challenging, but are you interested?

[fbrv]

Sure, I can give a try

[utam0k]

@fbrv I'm looking forward to your PR!

[utam0k]

@fbrv Hi! How is it going? If you have any trouble, I can help you.

[knight42]

@utam0k Hi! I would like to work on this!

[utam0k]

@knight42 Sure!