Fix broken links: Update README.md

[v-thepet]

PR into Azure/azureml-examples

Checklist

I have:

• [x] read and followed the contributing guidelines

Changes

• The Forecasting Beer/Beverage Production notebook was changed to Github Active Daily Users in PR https://github.com/Azure/azureml-examples/pull/953 So I updated the links and link texts to point to that Notebook.

• The filename of the Forecasting Hierarchical Timeseries notebook csv was wrong, should be hts-sample-train not hts_train.

• The link for image-classification-multiclass-batch-scoring/auto-ml-image-classification-multiclass-batch-scoring.ipynb looks like it was already fixed.

[v-thepet]

#sign-off