improve / fix code

• add golangci-lint action
• add docker lint action
• fix misused flag for basic auth
• fix lint issues
• fix docker lint issues
• improve tests, will improve more soon!
• show help text when called w/o URL
• add "-s" skip certificate check flag
• add "min" "max" values indicator for timeout (help text)
• fix some missing information in README
• add docker:lint task