`source` in install/project

in https://leanprover-community.github.io/install/project.html, there is a line

• If you have not logged in since you installed Lean and mathlib, then you may need to first type source ~/.profile or source ~/.bash_profile depending on your OS.

Someone just asked about this in the Xena Discord, about an error on Windows, which was bash: /c/Users/<their username>/.profile: No such file or directory. I told them to just close Git Bash and reopen it, which should do the same thing. Weirdly, if I do ls -a in Git Bash on my computer, I do see ~/.profile.

It might be worth mentioning explicitly what to do/expect on each OS, since right now it's expecting users to already be familiar with the command line. I would make a PR but it's been years since I last used Mac/Linux, and Windows behaviour seems to vary?

Start with install/project.html and review the quoted source ~/.profile and source ~/.bash_profile guidance alongside the Git Bash error described in the issue. Check the expected behavior on each referenced OS or shell, then update the page so users know what command or restart action to take and what successful setup should look like.