added offset section, restructured annotations tutorial, reworked

AnchoredOffsetbox section, embedded code that used to link out to
gallery examples, also minor consistency and linking tweaks throughout

Co-authored-by: Jody Klymak <jklymak@gmail.com>
Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
Co-authored-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>
Co-authored-by: Joseph Fox-Rabinovitz <madphysicist@users.noreply.github.com>

Author: 5 people