[DOC] Update CONTRIBUTING and README with developer installation, contributing and testing instructions

[jsheunis]

Closes #346

Changes proposed in this pull request:

README:

• Installation instructions were given more structure with headings. Divided into installation for:
  • local python environment,
  • conda environment
  • developer setup (which now links to updated CONTRUBTING, but could in future link to fully separate DEVELOPMENT_GUIDE à la scona)

CONTRIBUTING:

• Improved heading structure for the Making a change section
• Instructions on developer setup
• Included instructions for testing docs. Could link in future to the worked testing/contributing example Add worked contribution example #372

[codecov]

Codecov Report

Merging #375 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #375   +/-   ##
=======================================
  Coverage   79.74%   79.74%           
=======================================
  Files          40       40           
  Lines        2236     2236           
=======================================
  Hits         1783     1783           
  Misses        453      453

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 03ec6a2...dfc4baa. Read the comment docs.

[jbteves]

Just add the small correction from pip

[emdupre]

This is great, thanks @jsheunis ! 🌻

Just wanted to ping since it looks like there's only one small suggested revision, and I want to make sure this doesn't go stale. Let us know if we can help in any way !

[emdupre]

@all-contributors please add @jsheunis for documentation !

[allcontributors]

@emdupre

I've put up a pull request to add @jsheunis! 🎉

[jsheunis]

I'm a bit new to the process of reviews, suggestions, revisions, etc. I committed the change that @jbteves suggested, hope that was the right thing to do and the right way to do it!

[jbteves]

@jsheunis that's fine. When a reviewer makes a code suggestion GitHub offers the option to automatically create a commit and add it to the branch with the reviewer as co-author. If you make and push an otherwise identical commit manually on your own machine then the reviewer won't be co-authored unless you add a tag. That's the only real difference. I seriously doubt anybody will get bent out of shape about it. The nice thing with a suggested change is that it's just one click to add it if the original contributor agrees.

[emdupre]

This is great, thanks @jsheunis ! Committing the suggested change is perfect in my book.

@jbteves can you update your review if you're ok with it as-is and we'll get this merged ?

[jbteves]

LGTM