Fixed typo

Author: ScalarJerk

docs/00_pytorch_fundamentals.ipynb

@@ -1168,7 +1168,7 @@
     "\n",
     "These operations are often a wonderful dance between:\n",
     "* Addition\n",
-    "* Substraction\n",
+    "* Subtraction\n",
     "* Multiplication (element-wise)\n",
     "* Division\n",
     "* Matrix multiplication\n",