Apply suggestions from code review by Christian

Co-authored-by: Christian Zimpelmann <zimpelmann.christian@gmail.com>

docs/source/how_to/how_to_algorithm_selection.ipynb

@@ -22,7 +22,7 @@
     "## The four steps for selecting algorithms\n",
     "\n",
     "Algorithm selection is a mix of theory and experimentation. We recommend the following \n",
-    "for steps:\n",
+    "four steps:\n",
     "\n",
     "1. **Theory**: Based on the properties of your problem, start with 3 to 5 candidate algorithms. \n",
     "You may use the [decision tree below](link)\n",