Serve /.well-known/matrix/server with proper Content-Type

examples/apache/matrix-synapse.conf

@@ -56,6 +56,9 @@
 	<Files "/matrix/static-files/.well-known/matrix/server">
 		Require all granted
 	</Files>
+	<Location "/.well-known/matrix/server">
+		Header always set Content-Type "application/json"
+	</Location>
 	<Directory /matrix/static-files/.well-known/matrix/>
 		AllowOverride All
 		# Apache 2.4: