Test installation update

[learningboiz]

As per issue #2012, I have added a note under the test installation portion of the contribution documents.

I've suggested to wrap quotations around tests ('.[tests]') in case running installations on zsh produces an error.

Kindly let me know if the team would prefer these to be written somewhere else.

[carltongibson]

Hi @ElijahQuiazon — I merged #2011. Can you rebase after than please.

[learningboiz]

Hey @carltongibson,

Just read up on rebasing to grasp the general idea. Since it's my first time using it, I'm not entirely sure if I did it correctly — so kindly let me know if I should make any changes.

Thank you!

[bigfootjon]

Should we just modify the inline text? I.e. apply the following change:

-python -m pip install -e .[tests]
+python -m pip install -e '.[tests]'

instead of adding some documentation suffix. Quoting will work with bash just fine so this seems like a better cross-platform solution instead of adding some end-notes for one shell.

What do you think about that @learningboiz?