Thanks for reaching out Forrest! This article by the NRA answers your question better than I could:
americanrifleman.org/content/review-rock-island-armory-m206-revolver/
In short, while neither the pistol's markings nor its manual explicitly state that the M206 is rated for 38 Spl +P, Rock Island Armory has repeatedly stated the revolver is good to fire overpressure ammo.