Note stating manually adding custom subscription services removed in FF 63 (#2112)

* Note stating manually adding custom subscription services removed in FF 63

* Amended to mention bookmarklet and upcoming issues

1 files changed, 3 insertions, 1 deletions

diff --git a/docs/en/users/04_Subscriptions.md b/docs/en/users/04_Subscriptions.md
index 9faa7e7f0..4b40f691a 100644
--- a/docs/en/users/04_Subscriptions.md
+++ b/docs/en/users/04_Subscriptions.md
@@ -20,7 +20,9 @@ Bookmarklets are little scripts that you can execute to perform useful or frivol
 
 # Firefox subscription service
 
-You can manually add your FreshRSS app to the list of Firefox subscription services which will enable you to subscribe to sites which provide a feed link using the Firefox built-in "Subscribe" button. An in-depth process is described in the [official documentation](https://developer.mozilla.org/en-US/Firefox/Releases/2/Adding_feed_readers_to_Firefox) but you can use the following steps:
+NB: From version 63 and onwards Firefox has removed the ability to add your own subscription services that aren't standalone programs. This makes it impossible to add FreshRSS to the feed preview/subscription page, though this page is set to be removed from version 64 anyway (see [bugzilla](https://bugzilla.mozilla.org/show_bug.cgi?id=1477667)). You can use the bookmarklet mentioned above for an easy way to subscribe to feeds.
+
+If you're using a version pre-63 you can manually add your FreshRSS app to the list of Firefox subscription services, which enables you to subscribe to sites which provide a feed link using the Firefox built-in "Subscribe" button. An in-depth process is described in the [official documentation](https://developer.mozilla.org/en-US/Firefox/Releases/2/Adding_feed_readers_to_Firefox) but you can use the following steps:
 
   1. Open about:config in Firefox