GitLab

* docs: add xDiT to optimization methods

* fix: picture layout problem

* docs: add more introduction about xdit & apply suggestions

* Apply suggestions from code review
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

---------
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>