Update part-0.ipynb

downgraded ubuntu and fedora headre level from 3 to 4
rephrased instructiona about installing newer version on linux

Author: alaindomissy

part-0.ipynb

@@ -75,12 +75,12 @@
       "Python 3.4.1\n",
       "```\n",
       "\n",
-      "If you don't have Python installed or if you want a different version, you can install it as follows:"
+      "If you don't have Python installed or if you have a version older then 3.4 , you can install version 3.4 as follows:"
      ]
     },
     {
      "cell_type": "heading",
-     "level": 3,
+     "level": 4,
      "metadata": {},
      "source": [
       "Ubuntu"
@@ -99,7 +99,7 @@
     },
     {
      "cell_type": "heading",
-     "level": 3,
+     "level": 4,
      "metadata": {},
      "source": [
       "Fedora"
@@ -125,4 +125,4 @@
    "metadata": {}
   }
  ]
-}
+}