Adds referee screen and deities.

Updates bestiary with links to nonhuman racial modifiers.

src/pages/bestiary/thief.md

@@ -29,6 +29,7 @@ Someone skilled at stealth-based retrieval.
 -   **Leader**: 50% chance groups of 4+ are led by a higher level thief (1d4 HD higher).
 -   **Sneaky**: Use disguise or trickery to surprise victims.
 -   **Weapon Versatility**: May be found wielding various types of [weapons](https://www.planarvagabond.com/rules/combat.html#weapons).
+-   [**Non-human Modifiers**](./nonhuman-modifiers.html): Non-human thieves may have additional abilities or modified statistics.
 
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