Update LDA-Introduction.ipynb (aws#871)

removing typo

introduction_to_amazon_algorithms/lda_topic_modeling/LDA-Introduction.ipynb

@@ -108,7 +108,7 @@
     "\n",
     "* `bucket` - An S3 bucket accessible by this account.\n",
     "  * Used to store input training data and model data output.\n",
-    "  * Should be withing the same region as this notebook instance, training, and hosting.\n",
+    "  * Should be within the same region as this notebook instance, training, and hosting.\n",
     "* `prefix` - The location in the bucket where this notebook's input and and output data will be stored. (The default value is sufficient.)\n",
     "* `role` - The IAM Role ARN used to give training and hosting access to your data.\n",
     "  * See documentation on how to create these.\n",