Use built-in HSTS options for traefik #339
Description
Traefik has dedicated options for setting the Strict-Transport-Security Header. Traefik's Headers middleware has the options stsSeconds, stsIncludeSubdomains and stsPreload. (Documentation: https://doc.traefik.io/traefik/reference/routing-configuration/http/middlewares/headers/). I think I would be more appropriate to use the built-in tools provided in the Treafik configuration, instead of just adding a custom header entry. When I was looking for examples for configuring HSTS in Traefik I saw almost exclusively examples using these instead of the custom header approach suggested by ssl-config-generator. I have checked in the Traefik repository that these options were already available in the v2.0.0 release. I will open a PR to use these options in the >= 2.0.0 side of traefik config generator, so you can decide if you want to adopt this change or not.