Grammar update to Outside collaborators section of permission-levels-for-an-organization.md

[mirlenbrink]

What article on docs.github.com is affected?

permission-levels-for-an-organization.md
https://docs.github.com/en/github/setting-up-and-managing-organizations-and-teams/permission-levels-for-an-organization

What part(s) of the article would you like to see updated?

Outside collaborators
Small grammar update to Outside collaborators section to indicate possession by adding 's to "organization."

I believe instead of...

To keep your organization data secure...

it should be...

To keep your organization's data secure....