TorchRL, TensorDict version is not supported (+ Fix minor things)

[finani]

Thank you for your tremendous and fantastic approach, first.
It would be an enormous help to related works.

Nvidia Isaac Sim has a built-in Python, and its version is 3.7.
I think that is the reason the conda environment is python=3.7 (Installation).

A few days ago, I was trying to install OmniDrones and encountered an issue related to 'TensorDictParams'.
I have checked it is a new feature in TensorDict 0.2.0 (PR).
So, I tried to install TensorDict 0.2.0 (pip) and TorchRL 0.2.0 (pip) from pip, but they all support Python only from 3.8 to 3.11.
I got errors about Processing from Typing, which is a new feature in Python 3.8 when I installed them from git repos and ran OmniDrones.

Thankfully, I was able to successfully install and test OmniDrones with the newly updated guide.
However, I am just wondering if it will be okay in future versions.
(Is it okay to use packages that support Python 3.8 or higher in a Python 3.7 environment?)

I also fixed small problems with the docs and setup.py.
Thanks!

[btx0424]

Hi there!

The next release of Isaac Sim will support Python 3.8 to 3.10, according to the staff.

And thanks for your contribution! As some main dependencies are still not stable, I think there are currently some minor problems in the project. Feel free to raise an issue or PR if you encounter any.