Describe the publishing options in the docs

I noticed some helpful information around publishing a profile is absent in the [docs](https://profiler.firefox.com/docs/#/./guide-ui-tour?id=sharing-profiles) (UI Tour > Sharing Profiles section) that was mentioned to me during the All Hands workshop a few weeks back -- namely that some of what is shared by default in Nightly could contain PII or other sensitive information related to the current session.

It'd be great if each of the options were explained in terms of why you might want it checked, and why it is/isn't checked by default in various channels.


┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-180)