Add link to course

Author: NielsRogge

README.md

@@ -4,6 +4,8 @@ Hi there!
 
 This repository contains demos I made with the [Transformers library](https://github.com/huggingface/transformers) by 🤗 HuggingFace.
 
+NOTE: if you are not familiar with HuggingFace and/or Transformers, I highly recommend to check out our [free course](https://huggingface.co/course/chapter1), which introduces you to several Transformer architectures (such as BERT, GPT-2, T5, BART, etc.), as well as an overview of the HuggingFace libraries, including [Transformers](https://github.com/huggingface/transformers), [Tokenizers](https://github.com/huggingface/tokenizers), [Datasets](https://github.com/huggingface/datasets), [Accelerate](https://github.com/huggingface/accelerate) and the [hub](https://huggingface.co/).
+
 Currently, it contains the following demos:
 * BERT ([paper](https://arxiv.org/abs/1810.04805)): 
   - fine-tuning `BertForTokenClassification` on a named entity recognition (NER) dataset. [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/NielsRogge/Transformers-Tutorials/blob/master/BERT/Custom_Named_Entity_Recognition_with_BERT_only_first_wordpiece.ipynb)