fix default RETRY_HTTP_CODES value in docs
fix default RETRY_HTTP_CODES value in docs

pawelmhm/scrapy,pablohoffman/scrapy,elacuesta/scrapy,scrapy/scrapy,scrapy/scrapy,dangra/scrapy,eLRuLL/scrapy,elacuesta/scrapy,eLRuLL/scrapy,finfish/scrapy,pablohoffman/scrapy,finfish/scrapy,pablohoffman/scrapy,eLRuLL/scrapy,pawelmhm/scrapy,starrify/scrapy,wujuguang/scrapy,elacuesta/scrapy,dangra/scrapy,starrify/scrapy,finfish/scrapy,starrify/scrapy,pawelmhm/scrapy,dangra/scrapy,scrapy/scrapy,wujuguang/scrapy,wujuguang/scrapy