fix broken link to close JuliaAI/MLJ.jl#1189

Author: ablaom

docs/src/extended_examples/MNIST/notebook.jl

@@ -37,7 +37,7 @@ images, labels = MNIST(split=:train)[:];
 # must force the labels to have the `Multiclass` [scientific
 # type](https://juliaai.github.io/ScientificTypes.jl/dev/). For
 # more on this, see [Working with Categorical
-# Data](https://alan-turing-institute.github.io/MLJ.jl/dev/working_with_categorical_data/).
+# Data](https://juliaai.github.io/MLJ.jl/dev/working_with_categorical_data/).
 
 labels = coerce(labels, Multiclass);
 images = coerce(images, GrayImage);

docs/src/extended_examples/MNIST/notebook.md

@@ -44,7 +44,7 @@ In MLJ, integers cannot be used for encoding categorical data, so we
 must force the labels to have the `Multiclass` [scientific
 type](https://juliaai.github.io/ScientificTypes.jl/dev/). For
 more on this, see [Working with Categorical
-Data](https://alan-turing-institute.github.io/MLJ.jl/dev/working_with_categorical_data/).
+Data](https://juliaai.github.io/MLJ.jl/dev/working_with_categorical_data/).
 
 ````@example MNIST
 labels = coerce(labels, Multiclass);

docs/src/extended_examples/MNIST/notebook.unexecuted.ipynb

@@ -100,7 +100,7 @@
     "must force the labels to have the `Multiclass` [scientific\n",
     "type](https://juliaai.github.io/ScientificTypes.jl/dev/). For\n",
     "more on this, see [Working with Categorical\n",
-    "Data](https://alan-turing-institute.github.io/MLJ.jl/dev/working_with_categorical_data/)."
+    "Data](https://juliaai.github.io/MLJ.jl/dev/working_with_categorical_data/)."
    ],
    "metadata": {}
   },