Incremented the version to v24.1 (openai#2870)

Updated the gym version to v0.24 (openai#2839)

Update version.py

Update version.py

Updating MuJoCo docstrings (openai#2616)

* Changed Ant docstring

* Changed half cheetah docstring

* Changed Hopper docstring, modified formulations for Ant, HalfCheetah

* Changed humanoid docstring

* Changed HumanoidStandup, InvertedDoublependulum, InvertedPendulum docstrings

* Updated remaining docstrings, updated names of reward terms, added notes about info

Tests: don't use editable mode, use import-mode=append (openai#2429)

Updated registration.py (openai#2375)

* Updated registration.py

* Blacken

Bump version to 0.19.0

0.18.3 and release notes

update release note date