add notice about sup-application URL reversing from main app (#1496)
add notice about sup-application URL reversing from main app (#1496)


alex-eri/aiohttp-1,singulared/aiohttp,juliatem/aiohttp,KeepSafe/aiohttp,AraHaanOrg/aiohttp,arthurdarcet/aiohttp,pfreixes/aiohttp,arthurdarcet/aiohttp,AraHaanOrg/aiohttp,singulared/aiohttp,KeepSafe/aiohttp,KeepSafe/aiohttp,rutsky/aiohttp,z2v/aiohttp,z2v/aiohttp,pfreixes/aiohttp,juliatem/aiohttp,alex-eri/aiohttp-1,Eyepea/aiohttp,hellysmile/aiohttp,rutsky/aiohttp,alex-eri/aiohttp-1,rutsky/aiohttp,hellysmile/aiohttp,z2v/aiohttp,arthurdarcet/aiohttp,playpauseandstop/aiohttp,singulared/aiohttp