Rewording around `config` as a must have

We had the community call https://www.youtube.com/watch?reload=9&v=2D7Wjoj2lXc and it was clear the optional need for a config attribute or <py-config> or even <mpy-config> is not super clear in our docs.

We start the configuration section like this: https://docs.pyscript.net/2024.6.1/user-guide/configuration/

We need to tell PyScript how we want such Python environments to be configured

While true as a statement, this is a bit misleading in there to me: we don't need to tell anything to any interpreter ... unless we do.

This issue is to try brainstorming or improve that initial Configuration paragraph that sounds like a config is needed by all mean, and we already had users slightly confused about empty configs and the config meaning in general.

Start with the Configuration section at https://docs.pyscript.net/2024.6.1/user-guide/configuration/ and review its opening paragraph about configuring Python environments. Done means the paragraph clearly explains that config is optional and avoids suggesting that every interpreter needs one, including the case of an empty config.