add item to chengelog

CHANGELOG

@@ -91,6 +91,7 @@ v 8.7.0 (unreleased)
   - Diff design updates (colors, button styles, etc)
   - Copying and pasting a diff no longer pastes the line numbers or +/-
   - Add null check to formData when updating profile content to fix Firefox bug
+  - Disable spellcheck and autocorrect for username field in admin page
   - Delete tags using Rugged for performance reasons (Robert Schilling)
   - Add Slack notifications when Wiki is edited (Sebastian Klier)
   - Diffs load at the correct point when linking from from number