PR: Update Contributing Guide to latest version w/env setup and much more

[CAM-Gerlach]

Pull Request

Pull Request Checklist

• [x] Read and followed this repo's Contributing Guidelines
• [x] Based your PR on the latest version of the correct branch (master or 4.x)
• [x] Checked your writing carefully for correct English spelling, grammar, etc
• [x] Described your changes and the motivation for them below
• [x] Noted what issue(s) this pull request resolves, creating one if needed

Description of Changes

Updates the contributing guide to include the expanded and improved content from the standard version we now use on QtPy, the website, Docrepr and elsewhere, with much more helpful and comprehensive, step by step advice for new contributors walking them through the full process of getting a dev env set up, building the docs and creating a pull request. Most notably, it includes a detailed section walking them through creating a conda or venv/virtualenv environment, as pointed out by @hyounes4560 in #318 . It also includes new standard sections offering help at every step of the way, including:

• Cloning the repo
• Selecting the right branch
• Committing changes
• Pushing branches
• Opening a PR.
• Etc.

Furthermore, it links to a number of helpful Git tutorials for beginners at the beginning, as well as tweaks the text to be more friendly, and eliminates some unfriendly or not generally relevant bits.

As much as possible, it relies on the standard content we've developed, refined and use elsewhere, to offer the highest-quality help while minimizing maintenance burden.

@hyounes4560 any feedback welcome!

Issue(s) Resolved

Fixes #318

[hyounes4560]

@CAM-Gerlach can we add a tip/note on how to disable (--no-verify) / uninstall pre-commit hooks? just in case!

[hyounes4560]

@CAM-Gerlach I was about to submit a PR for this; ping me if you needed my help. Thank you

[CAM-Gerlach]

BTW, I will fix the small linkcheck issue (seems like Pylint re-organized their docs again) in another PR and rebase this one on that so the checks pass.

@CAM-Gerlach can we add a tip/note on how to disable (--no-verify) / uninstall pre-commit hooks? just in case!

Hmm, that's a good point. I definitely could, I just wasn't sure in what circumstances a normal contributor would need to do this—I've had to use --no-verify on some rare occasions, but that was when testing/upgrading the hooks themselves or doing other git black magic that I would never want a contributor to have to deal with themselves. Do you have a specific example I could mention?

@CAM-Gerlach I was about to submit a PR for this; ping me if you needed my help. Thank you

Oh, sorry about that! I'd love if you wouldn't mind reviewing it or have any other feedback/additions from your end, being someone who's both an experienced technical writer and was also recently introduced to this repo, and thus likely has much fresher insights on what would best serve new contributors.

[CAM-Gerlach]

I really like the new tone that the contribution guide has :)!

Thanks! Part of this was improving the language to make it more friendly and welcoming, though I think there still might be more we could do in that department in the future.

[CAM-Gerlach]

Thanks for your very helpful feedback as well, @ccordoba12 — it has significant improved the contributing guide further (which will eventually propagate to our other projects). I've applied each of your suggestions or a further tweaked version (to either refine them or fix/improve other related things in my own work that your comments helped me notice).

[CAM-Gerlach]

Looks like we're good to go on this one for now; we can always iterate further. Thanks @hyounes4560 , @steff456 and @ccordoba12 for your great feedback that really improved this further (and reminded me to do it to begin with)!