small addition (aimacode#582)

Author: antmarakis

text.ipynb

@@ -413,7 +413,7 @@
     "\n",
     "### Overview\n",
     "\n",
-    "With **Information Retrieval (IR)** we find documents that are relevant to a user's needs for information. A popular example is a web search engine, which finds and presents to a user pages relevant to a query. An IR system is comprised of the following:\n",
+    "With **Information Retrieval (IR)** we find documents that are relevant to a user's needs for information. A popular example is a web search engine, which finds and presents to a user pages relevant to a query. Information retrieval is not limited only to returning documents though, but can also be used for other type of queries. For example, answering questions when the query is a question, returning information when the query is a concept, and many other applications. An IR system is comprised of the following:\n",
     "\n",
     "* A body (called corpus) of documents: A collection of documents, where the IR will work on.\n",
     "\n",