Add a note about RUM indexes package on Debian/Ubuntu

diff --git a/docs/installation/releases_en.md b/docs/installation/releases_en.md
index 4645f7affd3ae17547e5c6b9963339456cabd636..39749b40b5ceac780b1a1f7478a4184fb507350d 100644 (file)
--- a/docs/installation/releases_en.md
+++ b/docs/installation/releases_en.md
@@ -41,9 +41,9 @@ apk add curl unzip ncurses postgresql posqtgresql-contrib nginx certbot
 #### (Optional) Installing RUM indexes
 RUM indexes are an alternative indexing scheme that is not included in PostgreSQL by default. You can read more about them on the [Configuration page](config.html#rum-indexing-for-full-text-search). They are completely optional and most of the time are not worth it, especially if you are running a single user instance (unless you absolutely need ordered search results).
 
-Debian/Ubuntu:
+Debian/Ubuntu (available only on Buster/19.04):
 ```sh
-apt install postgresql-rum
+apt install postgresql-11-rum
 ```
 Alpine:
 ```sh