Remove outdated fixtures description in README (#291)

See #260 and #290.

Co-authored-by: Michael Howitz <icemac@gmx.net>

Author: The-Compiler

README.rst

@@ -221,7 +221,6 @@ be marked as failed.
 Compatibility
 -------------
 
-* This plugin may *not* be used with class, module, and package level fixtures.
 * This plugin is *not* compatible with pytest-xdist's --looponfail flag.
 * This plugin is *not* compatible with the core --pdb flag.
 * This plugin is *not* compatible with the plugin