Mention the "-r" option in the Neptune docs in the right context

Issue AUTOSUITE-1110 was closed as out of scope for appman. I still wish that we tell the user how to handle such situations. Along that, I saw that the current docs in https://doc-snapshots.qt.io/neptune3ui-dev/neptune3ui-install.html de-facto tell the user to always start neptune with "-r". It is actually not needed. "-r" should still be mentioned as in the note under the point "5" in "Build and run". Maybe we can do an early version of AUTOSUITE-837 and expand the "Note" to a new, but small for now, section "Handling problems" and mention at least the sense of the "-r" option