CONTRIBUTING.MD appears to be stale

[tdcox]

The documentation relating to building jx appears to be out of date. For example, there are references to Go 1.13 not being supported but following the setup instructions will result in Go 1.16 being installed. It is not clear where things have diverged from v2 practice.

[ankitm123]

It is not clear where things have diverged from v2 practice.

I can think of 2 reasons:

• JX v2 was a monolith (everything was in one big repo), so there was just one place to update the documentation, now there are lot of repositories each with it's own contributing.md file, which makes it harder to update ...
• Less active developers in v3

I will be upgrading the version of go in the next week to 1.17, once that is done, I am thinking of just pointing the READ me to this link: https://jenkins-x.io/community/code/ (ofc this is stale, and needs to be updated as well). Then all we need to do is update it at one place, and ensure those docs are up to date. wdyt?