Add pref. to Preferences list

diff --git a/docs/index.md b/docs/index.md
index 6db2975dcb39a55ecddffb728f58bf8006431fbc..8cda2fd20fd41ca035b6876b77c7efd5bc5a2836 100644 (file)
--- a/docs/index.md
+++ b/docs/index.md
@@ -4596,6 +4596,7 @@ media.
 network.
 pdfjs. (Firefox 84, Firefox ESR 78.6)
 places.
+pref.
 print.
 signon. (Firefox 83, Firefox ESR 78.5)
 spellchecker. (Firefox 84, Firefox ESR 78.6)