Merge pull request #257 from hrushikesh-s/matbench-latest

Adding the formula used to calculate Scaled error for classification tasks to the docs

scripts/doc_snippets/index_0.md

@@ -4,3 +4,8 @@ $$
 \text{Scaled Error} = \frac{\text{MAE}}{\text{MAD}} = \frac{\sum_i^N | y_i - y_i^{pred} |}{\sum_i^N | y_i - \bar{y} | }
 $$
 
+While, scaled errors for classifications are assessed as:
+
+$$
+\text{Scaled Error} = \frac{1 - \text{ROCAUC}}{0.5}
+$$