Update Community_Guidelines.md, Sections 3 and 4 (partial)

[bradtchapman]

This is the beginning of my effort to expand upon the shorthand writing style of the community guidelines.

I felt that some key policy and etiquette details were missing, some clarification was needed in places, and I split up the description of the jobs-board and jobs-chat channels.

I completed this much on my phone in 45 minutes, but editing on GitHub is a pain in the ass on a mobile phone due to idiosyncrasies and/or bugs with GitHub where tapping the backspace button too rapidly ends up deleting more than I wanted to.

I will finish revising this on a computer this afternoon and over the weekend.

[neilmartin83]

@bradtchapman thank you. I've started off with in-line comments for markdown structural changes that are needed. There are other changes I can see that I think the team will want to review in more detail. A mix of general structure, formatting as well as specific content/language as well (so a bit of everything).

As this is a large PR, it may not make it into the CoC release next week as we likely won't have time to fully review all your changes by our deadline. Don't worry - it just means it'll sit here and we'll continue to work through/review/discuss etc after that.

[bradtchapman]

Good morning. Looking forward to others' comments and revisions on this.

[neilmartin83]

This is now based from the new master branch, ready to continue the review :)

[kseyoss]

Minor typo in section 1: "Do not take the bait of disrepectful"

(with apologies - noticing things like this is a curse).