Resolved openCypher query issue (#501)

Resolved "Variable `n` already declared (line 3, column 9 (offset: 46))" issue.

Author: kevinphillips81

src/graph_notebook/notebooks/01-Getting-Started/01-About-the-Neptune-Notebook.ipynb

@@ -272,9 +272,9 @@
    "source": [
     "%%oc\n",
     "\n",
-    "CREATE (n:Language {name:\"Gremlin\"})\n",
-    "CREATE (n:Language {name:\"Cypher\"})\n",
-    "CREATE (n:Language {name:\"SPARQL\"})"
+    "CREATE (a:Language {name:\"Gremlin\"})\n",
+    "CREATE (b:Language {name:\"Cypher\"})\n",
+    "CREATE (c:Language {name:\"SPARQL\"})"
    ],
    "metadata": {
     "collapsed": false,