Documentation/Build Guide: Missing step to run build command

[ethanchristensen01]

The Build Guide should include a step to run npm build in the "Quickstart" and "Build the Code" sections.

If npm build is not run before npm serve, the shaders are never converted from .glsl to .js files, and the dev server crashes when it cannot find them. This seems to be documented in the VSCode Guide, but this note is missing from the Build Guide.

[devkthines]

I would like to tackle this ticket, From JTC.

[ggetz]

@devkthines You got it!