Add helpful resources for learning Manim in the landing page.

Nobody has claimed this yet.

## Enhancement proposal

I suggested adding a channel in the discord server called `#beginner-resources` that would help beginners get started with Manim.

@behackl also suggested adding this type of information in the docs/ landing page.

I think this would be a good idea! We could probably add some of the resources we compiled from the `?sp tutorials` snippet:

```
Most tutorials online are outdated, but here are some that aren't:
Try manim:
https://try.manim.community/
kolibril13's flying frames:
https://flyingframes.readthedocs.io/en/latest/
Brian Amadee's YouTube tutorials:
https://www.youtube.com/watch?v=MOv6yN7b2aI&list=PLWOlLjdyZm2NQD1YZmEPB0dwbd0yKINAT
Theorem of Beethoven's YouTube tutorials:
https://www.youtube.com/watch?v=mbjuZa5r-z4
Our documentation:
https://docs.manim.community/en/latest/tutorials.html
```

If there any other good resources out there, feel free to list them below 👍

Start in the docs/ landing page and review the resources collected from the `?sp tutorials` snippet. Add the beginner-oriented links listed in the issue, check that each URL is valid, and confirm the landing page clearly presents them as learning resources.

Written by the indexing model from the issue text.