Fix some wording issues in the notes (#695)

ch05/01_main-chapter-code/ch05.ipynb

@@ -813,7 +813,7 @@
    "id": "379330f1-80f4-4e34-8724-41d892b04cee",
    "metadata": {},
    "source": [
-    "- A quick check that the text loaded ok by printing the first and last 100 words"
+    "- A quick check that the text loaded ok by printing the first and last 99 characters"
    ]
   },
   {
@@ -838,7 +838,7 @@
     }
    ],
    "source": [
-    "# First 100 characters\n",
+    "# First 99 characters\n",
     "print(text_data[:99])"
    ]
   },
@@ -864,7 +864,7 @@
     }
    ],
    "source": [
-    "# Last 100 characters\n",
+    "# Last 99 characters\n",
     "print(text_data[-99:])"
    ]
   },