Psychology subsection has only 4 entries

[yakew7]

The ### Psychology subsection under By Subject currently has only 4 entries (CrashCourse, Fiveable, Seneca Learning, Simply Psychology). Add 1-2 more genuine, verified psychology study resources.

[yakew7]

Added OpenStax Psychology 2e (free peer-reviewed textbook) and tutor2u Psychology to Psychology (4 -> 6 entries). Both verified live. Counts regenerated, check-list-format passes.