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

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