Minor changes

- Added missing environment variables to Dockerfile
- Constant ca certificates filepath
- Removed dns/os.go unused file
- Formatting improvements
- Added comments
- Readme TODOs update

internal/dns/conf.go

@@ -52,7 +52,7 @@ func generateUnboundConf(settings settings.DNS, client network.Client, logger lo
 		"hide-identity":    "yes",
 		"hide-version":     "yes",
 		// Security
-		"tls-cert-bundle":       "\"/etc/ssl/certs/ca-certificates.crt\"",
+		"tls-cert-bundle":       fmt.Sprintf("%q", constants.CACertificates),
 		"root-hints":            fmt.Sprintf("%q", constants.RootHints),
 		"trust-anchor-file":     fmt.Sprintf("%q", constants.RootKey),
 		"harden-below-nxdomain": "yes",