Tweak the docs for Page::modular() and Page::modularTwig()
Tweak the docs for Page::modular() and Page::modularTwig()

Fixes #724

joeyhenricks/a-broke-vegan,Vivalldi/grav,getgrav/grav,userfrosting/learn,Vivalldi/grav,userfrosting/learn,JamesPan/gravbox,notklaatu/grav,gigago/grav,joeyhenricks/a-broke-vegan,shortsofia/testesitegrav.github.io,userfrosting/learn,sylvestrelucia/grav,tomzx/blog.tomrochette.com,toovy/grav,sylvestrelucia/grav,stell/grav,toovy/grav,tomzx/blog.tomrochette.com,ccardinaux/grav-test,getgrav/grav,webuxr/iamrs,JamesPan/gravbox,tomzx/blog.tomrochette.com,notklaatu/grav,sylvestrelucia/grav,JamesPan/gravbox,userfrosting/learn,dimayakovlev/grav,dimayakovlev/grav,sylvestrelucia/grav,tomzx/blog.tomrochette.com,JamesPan/gravbox,Sommerregen/grav