Add headers for more security
Add headers for more security

- X-Frame-Options so browser cannot render page in a frame
- X-Content-Tyoe-Options to disable content type sniffing
- X-XSS-Protection to ensure the cross-site scripting browser filter is enabled
- Strict-Transport-Security to instruct the browser to only access a web
application over a secure connection and and remember it for 12 months

UKHomeOffice/docker-nginx-proxy,UKHomeOffice/docker-ngx-openresty