Update interpolation documentation & fix some typos
Summary: Removed the old note regarding interpolation being disabled when there is more than one label. Also fixed some documentation typos in various spots.
Test Plan: Proof read
Reviewers: O1 MITK Reviewer Group I, kislinsk
Reviewed By: O1 MITK Reviewer Group I, kislinsk
Maniphest Tasks: T30162
Differential Revision: https://phabricator.mitk.org/D853