Mention Z shell specifics in install instructions

[glatterf42]

As discovered by @setupelz just now, users of the Z shell (zsh) might run into this error message when trying to install from source:

% pip install --editable .[docs,tests,tutorial]
zsh: no matches found: .[docs,tests,tutorial]

This issue is explained wonderfully here:

zsh uses square brackets for globbing / patern matching

Consequently, the brackets need to be escaped or inside quotes like pip install -e '.[docs,tests,tutorial]' for the command to work. This could either be a Known Issue or a footnote on the specific command.

We might want to include the same note in the other repos of our stack as well.

[khaeru]

Using the lens of #771:

• For the quick-start install:
  • I think we should state an assumption that users will use the default terminal on their respective OS. I don't think zsh is default on any OS.
• For the full/exhaustive install guide
  • We can definitely include a footnote like "If using zsh, recall that [...] is a glob operator, so the argument to pip must be quoted appropriately." (Or use the URL in the SO answer.) In such cases, it's always best to directly point users to the first-party docs for the tools they are using.