doh support: make no TLS config fatal (#4162)

without TLS you can't have a functioning DoH server as no client will be
able to talk to it. Make this a fatal failure.

Add some extra docs on how to start a DoH capable server.

Signed-off-by: Miek Gieben <miek@miek.nl>

1 files changed, 4 insertions, 1 deletions

diff --git a/README.md b/README.md
index a8476a7b1..efb5def84 100644
--- a/README.md
+++ b/README.md
@@ -195,13 +195,16 @@ And for DNS over HTTP/2 (DoH) use:
 ~~~ corefile
 https://example.org {
     whoami
+    tls mycert mykey
 }
 ~~~
 
+Note that you must have the *tls* plugin configured as DoH requires that to be setup.
+
 Specifying ports works in the same way:
 
 ~~~ txt
-grpc://example.org:1443 {
+grpc://example.org:1443 https://example.org:1444 {
     # ...
 }
 ~~~