Typo fix in using_citations.ipynb

"This guide teach you" --> "This guide teaches you"

misc/using_citations.ipynb

@@ -6,7 +6,7 @@
  "source": [
  "# Having Claude Cite its Sources\n",
  "\n",
- "This guide teach you how to have Claude cite sources when referencing documents given to it in context. Adding citations can make your application more reliable and transparent -- when a user can click through to a piece of supporting \n",
+ "This guide teaches you how to have Claude cite sources when referencing documents given to it in context. Adding citations can make your application more reliable and transparent -- when a user can click through to a piece of supporting \n",
  "documentation, it will help them develop trust in generated outputs."
  ]
  },