Add some comments for an obscure feature

dnscrypt-proxy/example-dnscrypt-proxy.toml

@@ -637,14 +637,15 @@ fragments_blocked = ['cisco', 'cisco-ipv6', 'cisco-familyshield', 'cisco-familys
 
 
 
-################################
-#   TLS Client Authentication  #
-################################
+#################################################################
+#        Certificate-based client authentication for DoH        #
+#################################################################
 
+# Use a X509 certificate to authenticate yourself when connecting to DoH servers.
 # This is only useful if you are operating your own, private DoH server(s).
 # (for DNSCrypt, see the `query_meta` feature instead)
 
-[tls_client_auth]
+# [tls_client_auth]
 
 # creds = [
 #    { server_name='myserver', client_cert='client.crt', client_key='client.key' }