04_mnist basics typo correction (#299)

Found typo "experssion" instead of "expression" in markup above mnist_distance function cell

04_mnist_basics.ipynb

@@ -5867,7 +5867,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.7"
+   "version": "3.8.5"
   },
   "toc": {
    "base_numbering": 1,