Soapbox nginx: fix ld+json ActivityPub route

installation/mastodon.conf

@@ -3,6 +3,10 @@
 #
 # Edit this file to change occurences of "example.com" to your own domain.
 
+# Note: if this line causes an error, move it to nginx.conf
+# https://github.com/nginx-proxy/nginx-proxy/issues/1365#issuecomment-668421898
+map_hash_bucket_size 128;
+
 map $http_upgrade $connection_upgrade {
   default upgrade;
   ''      close;
@@ -12,8 +16,7 @@ map $http_upgrade $connection_upgrade {
 map $http_accept $activitypub_location {
   default /index.html;
   "application/activity+json" @proxy;
-  # Increase `map_hash_bucket_size` to enable this route:
-  # 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"' @proxy;
+  'application/ld+json; profile="https://www.w3.org/ns/activitystreams"' @proxy;
 }
 
 upstream backend {