build(docker): include content type header for transcript files

docker/production/castopod/config.template.json

@@ -37,7 +37,13 @@
   "settings": {
     "http": {
       "body_read_timeout": $CP_TIMEOUT,
-      "max_body_size": $CP_MAX_BODY_SIZE_BYTES
+      "max_body_size": $CP_MAX_BODY_SIZE_BYTES,
+      "static": {
+        "mime_types": {
+          "text/vtt": [".vtt"],
+          "text/srt": [".srt"]
+        }
+      }
     }
   }
 }

docker/production/web-server/nginx.template.conf

@@ -9,6 +9,10 @@ events {
 
 http {
     include       /etc/nginx/mime.types;
+    types {
+	    text/vtt vtt;
+	    text/srt srt;
+    }
     default_type  application/octet-stream;
 
     log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '