Update search_json_examples.ipynb: Fix the old import indexDefinition -> index_definition (redis#3652)

Fix the old import indexDefinition -> index_definition

Author: ShubhamKaudewar

docs/examples/search_json_examples.ipynb

@@ -30,7 +30,7 @@
     "import redis.commands.search.aggregation as aggregations\n",
     "import redis.commands.search.reducers as reducers\n",
     "from redis.commands.search.field import TextField, NumericField, TagField\n",
-    "from redis.commands.search.indexDefinition import IndexDefinition, IndexType\n",
+    "from redis.commands.search.index_definition import IndexDefinition, IndexType\n",
     "from redis.commands.search.query import NumericFilter, Query\n",
     "\n",
     "\n",