Formatting typo in model architectures list in chapter2/2.mdx

In Chapter 2's ["Model heads: Making sense out of numbers"](https://github.com/huggingface/course/blob/main/chapters/en/chapter2/2.mdx#model-heads-making-sense-out-of-numbersmodel-heads-making-sense-out-of-numbers) section a non-exhaustive list of model architectures are listed, but the formatting seems to have included additional unnecessary `*`:

```
- `*Model` (retrieve the hidden states)
- `*ForCausalLM`
- `*ForMaskedLM`
- `*ForMultipleChoice`
- `*ForQuestionAnswering`
- `*ForSequenceClassification`
- `*ForTokenClassification`
- and others 🤗
```
> Reference to specific lines: [2.mdx#L225-L231](https://github.com/huggingface/course/blame/aca889a8fb33bf11ef02953c88cb03f15ded4655/chapters/en/chapter2/2.mdx#L225-L231)