Update web_traversal example: add module docstring
Update web_traversal example: add module docstring

hellysmile/aiohttp,vaskalas/aiohttp,elastic-coders/aiohttp,sterwill/aiohttp,jojurajan/aiohttp,moden-py/aiohttp,arthurdarcet/aiohttp,singulared/aiohttp,arthurdarcet/aiohttp,andyaguiar/aiohttp,alexsdutton/aiohttp,noodle-learns-programming/aiohttp,mind1master/aiohttp,arthurdarcet/aiohttp,esaezgil/aiohttp,KeepSafe/aiohttp,decentfox/aiohttp,elastic-coders/aiohttp,z2v/aiohttp,decentfox/aiohttp,AraHaanOrg/aiohttp,KeepSafe/aiohttp,juliatem/aiohttp,z2v/aiohttp,rutsky/aiohttp,rutsky/aiohttp,AlexLisovoy/aiohttp,jashandeep-sohi/aiohttp,noplay/aiohttp,AlexLisovoy/aiohttp,alex-eri/aiohttp-1,panda73111/aiohttp,juliatem/aiohttp,saghul/aiohttp,Srogozins/aiohttp,AraHaanOrg/aiohttp,jettify/aiohttp,vedun/aiohttp,jettify/aiohttp,hellysmile/aiohttp,jettify/aiohttp,Insoleet/aiohttp,Eyepea/aiohttp,avanov/aiohttp,flying-sheep/aiohttp,vaskalas/aiohttp,saghul/aiohttp,rutsky/aiohttp,mind1master/aiohttp,playpauseandstop/aiohttp,jashandeep-sohi/aiohttp,mind1master/aiohttp,vasylbo/aiohttp,alex-eri/aiohttp-1,moden-py/aiohttp,morgan-del/aiohttp,alexsdutton/aiohttp,alex-eri/aiohttp-1,pathcl/aiohttp,iksteen/aiohttp,elastic-coders/aiohttp,z2v/aiohttp,esaezgil/aiohttp,iksteen/aiohttp,esaezgil/aiohttp,KeepSafe/aiohttp,jashandeep-sohi/aiohttp,singulared/aiohttp,noplay/aiohttp,pfreixes/aiohttp,alunduil/aiohttp,decentfox/aiohttp,vaskalas/aiohttp,jojurajan/aiohttp,panda73111/aiohttp,pfreixes/aiohttp,danielnelson/aiohttp,panda73111/aiohttp,moden-py/aiohttp,singulared/aiohttp