DOC: add info on importing tabular data

doc/widgets/importimages.md

@@ -33,3 +33,8 @@ Now we can proceed with standard machine learning methods. We will send images t
 Then we will use **Test & Score** and **Logistic Regression**, to build a model for predicting the author of a painting. We get a perfect score? How come? It turns out, these were the images the *Painters* embedder was trained on, so a high accuracy is expected.
 
 ![](images/ImportImages-Example.png)
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+Note
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+If you have a list of images in a tabular format, add *type=image* to the third header row of the column containing the path to images.