Update compiled_asset_path in default_plugins.md

[aried3r]

Was changed in #656.

I wonder if, for backwards compatibility, we shouldn't leave compiled_asset_path alone and create a compiled_asset_dirs?

Anyway, this documents the current state.

[lovro-bikic]

Thank you for the PR. I've opted for preserving backward compatibility and have therefore reverted #656, so I'll close this.