docs: update Exa integration examples (#31547)

## Description

Updating Exa integration documentation to showcase the latest features
and best practices.

## Changes

- Added examples for `ExaSearchResults` tool with advanced search
options
- Added examples for `ExaFindSimilarResults` tool
- Updated agent example to use LangGraph
- Demonstrated text content options, summaries, and highlights
- Included examples of search type control and live crawling

## Additional Context

I'm from the Exa team updating our integration documentation to reflect
current capabilities and best practices.

docs/docs/integrations/providers/exa_search.ipynb

@@ -50,17 +50,7 @@
     {
       "cell_type": "markdown",
       "metadata": {},
-   "source": [
+      "source": "## Tools\n\nYou can use Exa as an agent tool as described in the [Exa tool calling docs](/docs/integrations/tools/exa_search#use-within-an-agent).\n\nSee a [usage example](/docs/integrations/tools/exa_search).\n\n### ExaFindSimilarResults\n\nA tool that queries the Metaphor Search API and gets back JSON."
-    "## Tools\n",
-    "\n",
-    "You can use Exa as an agent tool as described in the [Exa tool calling docs](/docs/integrations/tools/exa_search#using-the-exa-sdk-as-langchain-agent-tools).\n",
-    "\n",
-    "See a [usage example](/docs/integrations/tools/exa_search).\n",
-    "\n",
-    "### ExaFindSimilarResults\n",
-    "\n",
-    "A tool that queries the Metaphor Search API and gets back JSON."
-   ]
     },
     {
       "cell_type": "code",