Broken link to t5 doc in chapter 1

The link to the T5 docs is broken in chapter 1.5 [How 🤗 Transformers solve tasks](https://github.com/huggingface/course/blob/main/chapters/en/chapter1/5.mdx) in the summarization section in line 134:

> Encoder-decoder models like [BART](https://huggingface.co/docs/transformers/model_doc/bart) and [T5](model_doc/t5) are designed for the sequence-to-sequence pattern of a summarization task. We'll explain how BART works in this section, and then you can try finetuning T5 at the end.

It should be updated to https://huggingface.co/docs/transformers/model_doc/t5