Layers documentation (#5475)
Layers documentation (#5475)

Fixes #3111
OrchardCMS/Brochard,petedavis/Orchard2,petedavis/Orchard2,OrchardCMS/Brochard,xkproject/Orchard2,xkproject/Orchard2,petedavis/Orchard2,stevetayloruk/Orchard2,stevetayloruk/Orchard2,xkproject/Orchard2,OrchardCMS/Brochard,stevetayloruk/Orchard2,xkproject/Orchard2,xkproject/Orchard2,petedavis/Orchard2,stevetayloruk/Orchard2,stevetayloruk/Orchard2