update comments for placeholders too

Co-authored-by: Francis Lavoie <[email protected]>

Author: WeidiDeng

modules/caddyhttp/app.go

@@ -82,7 +82,7 @@ func init() {
 // `{http.request.tls.proto}` | The negotiated next protocol
 // `{http.request.tls.proto_mutual}` | The negotiated next protocol was advertised by the server
 // `{http.request.tls.server_name}` | The server name requested by the client, if any
-// `{http.request.tls.ech_accepted}` | ECH offered by the client and accepted by the server
+// `{http.request.tls.ech}` | Whether ECH was offered by the client and accepted by the server
 // `{http.request.tls.client.fingerprint}` | The SHA256 checksum of the client certificate
 // `{http.request.tls.client.public_key}` | The public key of the client certificate.
 // `{http.request.tls.client.public_key_sha256}` | The SHA256 checksum of the client's public key.