add note about plasma integration breaking screen sharing

README.md

@@ -1,5 +1,6 @@
 # Miscellaneous topics that I'm too lazy to script
-## Firefox with tree-style tabs
+## Firefox 
+### tree-style tabs
 1. Go to `about:config` in Firefox and make sure that
    `toolkit.legacyUserProfileCustomizations.stylesheets` is set to `true`.
 2. Close Firefox.
@@ -8,3 +9,9 @@
 ```
 @import url(chrome/hide_tabs_toolbar_v2.css)
 ```
+### screen sharing broken in MS Teams (and maybe others?)
+This is caused by the "Plasma Integration" plugin. You need to disable a
+certain functionality for it to work:
+1. Go to Manage extensions->Plasma Integration->Preferences and disable/uncheck
+   "Enhanced Media Controls".
+2. Restart Firefox for change to take effect.