minor typo: instance norm -> group norm

Author: tatsuookubo

labml_nn/normalization/group_norm/readme.md

@@ -15,6 +15,6 @@ This is based on the observation that classical features such as
 The paper proposes dividing feature channels into groups and then separately normalizing
 all channels within each group.
 
-Here's a [CIFAR 10 classification model](https://nn.labml.ai/normalization/group_norm/experiment.html) that uses instance normalization.
+Here's a [CIFAR 10 classification model](https://nn.labml.ai/normalization/group_norm/experiment.html) that uses group normalization.
 
 [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/labmlai/annotated_deep_learning_paper_implementations/blob/master/labml_nn/normalization/group_norm/experiment.ipynb)