Use existing Strata docs from the Momentum Wiki

[InevitablyDivinity]

We should incorporate some of the pages from the Momentum Wiki here, since they cover features of the engine that are independent of Momentum.

AngelScript Hammer API

• Chaos Hammer AngelScript Classes
• Chaos Hammer AngelScript Enums
• Chaos Hammer AngelScript Examples
• Chaos Hammer AngelScript Global Functions
• Chaos Hammer AngelScript Global Properties
• Chaos Hammer AngelScript Value Types

Guides

• How to Use World Portals

Shaders

• Modulate Shader
• Parallax-Corrected Cubemaps
• The PBR Shader

[ashifolfi]

I got the AngelScript docs copied over in a PR (if any suggestions are to be had regarding the info please make them!) but the others here might take a bit longer to do given they're still written with momentum in mind so changes are a bit more involved to make generic Strata Source variants of the info.