DOC: this is in whats new already

This is a new feature not an API change.

Author: tacaswell

doc/api/prev_api_changes/api_changes_3.11.0/behavior.rst

@@ -160,14 +160,6 @@ containing tuples of:
 
 Specifically, the glyph index was added after the character code.
 
-New environment variable to ignore system fonts
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-System fonts may be ignored by setting the :envvar:`MPL_IGNORE_SYSTEM_FONTS`; this
-suppresses searching for system fonts (in known directories or via some
-platform-specific subprocess) as well as limiting the results from
-`.FontManager.findfont`.
-
 SVG links open in new tab or window
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~