Fixed simple grammatical mistake (#1952)

website/docs/tutorial/introduction.ipynb

@@ -18,7 +18,7 @@
     "> _The whole is greater than the sum of its parts._<br/>\n",
     "> -**Aristotle**\n",
     "\n",
-    "While there are many definitions of agents, in AutoGen, an agent is an entity that can send messages, receive messages and generate reply using models, tools, human inputs or a mixture of them.\n",
+    "While there are many definitions of agents, in AutoGen, an agent is an entity that can send messages, receive messages and generate a reply using models, tools, human inputs or a mixture of them.\n",
     "This abstraction not only allows agents to model real-world and abstract entities, such as people and algorithms, but it also simplifies implementation of complex workflows as collaboration among agents.\n",
     "\n",
     "Further, AutoGen is extensible and composable: you can extend a simple agent with customizable components and create workflows that can combine these agents and power a more sophisticated agent, resulting in implementations that are modular and easy to maintain.\n",