How to Get Help page should include IRC password set up instructions and channel from Wiki

https://docs.opendaylight.org/en/latest/getting-started-guide/how-to-get-help.html should include more detailed steps to help possibly interested new contributors get on IRC, notably how to get set up with the password thing we are now enforcing, which is a hurdle for some people.

We could also include the channels list from https://wiki.opendaylight.org/view/IRC

version: Latest
page: getting-started-guide/how-to-get-help