Add Instructions for upgrading ScubaGoggles

[adhilto]

💡 Summary

Add instructions to the README for how to upgrade ScubaGoggles.

Motivation and context

Users may need help upgrading from older releases to the latest.
 

Implementation notes

• Say a user downloaded the ScubaGoggles code when v0.2 was released by cloning the repo (as opposed to downloading the release), then used pip install . When v0.3 is released, if all they do is pull the latest from main, scubagoggles gws will break.
• If a user takes the route of downloading the release zip, how do they upgrade scubaggogles to the latest release? (it should be as simple as running python -m pip install . from the newly downloaded folder, but it might be useful to state that).

Acceptance criteria

• Documentation has been updated