fix: move readthedocs link from "testcontainers-python" to "testcontainers" in README.md

[vini-md]

We need to change here too:

Follow the new link: https://testcontainers.readthedocs.io/en/latest/

Thank you @alexanderankin

[alexanderankin]

im torn because i dont want to just deadlink the old one, there's probably links to it from places.

[alexanderankin]

this is still on hold as i dont have the required access to actually setup a WEB hook on this repo - so my testcontainers site on readthedocs is actually being manually updated (re-ran) by me.

@kiview - if you can send me your username on readthedocs i can transfer you the testcontainers name and you can click the required buttons on readthedocs.

@SergeyPirogov - my username is daveankin on https://readthedocs.org so maybe you can add me on the old one.

[alexanderankin]

another benefit of resolving this is docs for new containers like #508 can get published

[vini-md]

another benefit of resolving this is docs for new containers like #508 can get published

exactly, the docs are stuck in the old version, this is not good for Developer Experience

[alexanderankin]

i now have access on readthedocs for https://readthedocs.org/dashboard/testcontainers-python/edit/ so it is just a matter of coordinating with @kiview or someone else with admin access to the github to actuall re-install the webhook.