Update doc and changelog

Author: araffin

docs/guide/vec_envs.rst

@@ -148,6 +148,9 @@ Consider the following example for a custom env:
 	print(vec_env.env_method("get_wrapper_attr", "mu"))
 	# Change `mu` attribute via the setter
 	vec_env.env_method("set_mu", "mu", 0.1)
+	# If the variable exists, you can also use `set_wrapper_attr` to set it
+	assert vec_env.has_attr("mu")
+	vec_env.env_method("set_wrapper_attr", "mu", 0.1)
 
 
 In this example ``env.mu`` cannot be accessed/changed directly because it is wrapped in a ``VecEnv`` and because it could be wrapped with other wrappers (see `GH#1573 <https://github.com/DLR-RM/stable-baselines3/issues/1573>`_ for a longer explanation).

docs/misc/changelog.rst

@@ -3,7 +3,7 @@
 Changelog
 ==========
 
-Release 2.6.0a1 (WIP)
+Release 2.6.0a2 (WIP)
 --------------------------
 
 
@@ -14,6 +14,7 @@ New Features:
 ^^^^^^^^^^^^^
 - Added ``has_attr`` method for ``VecEnv`` to check if an attribute exists
 - Added ``LogEveryNTimesteps`` callback to dump logs every N timesteps (note: you need to pass ``log_interval=None`` to avoid any interference)
+- Added Gymnasium v1.1 support
 
 Bug Fixes:
 ^^^^^^^^^^
@@ -36,11 +37,14 @@ Others:
 ^^^^^^^
 - Updated black from v24 to v25
 - Improved error messages when checking Box space equality (loading ``VecNormalize``)
+- Updated test to reflect how ``set_wrapper_attr`` should be used now
 
 Documentation:
 ^^^^^^^^^^^^^^
 - Clarify the use of Gym wrappers with ``make_vec_env`` in the section on Vectorized Environments (@pstahlhofen)
 - Updated callback doc for ``EveryNTimesteps``
+- Added doc on how to set env attributes via ``VecEnv`` calls
+
 
 Release 2.5.0 (2025-01-27)
 --------------------------