docs: add You.com MCP tools for search, research, and content extraction (#5563)

* docs: add You.com MCP integration documentation for crewAI

Add documentation pages for integrating You.com's remote MCP server
with crewAI agents, covering web search, research, and content
extraction tools via the MCP protocol.

Pages added:
- Overview with DSL and MCPServerAdapter integration approaches
- you-search: web/news search with advanced filtering
- you-research: multi-source research with cited answers
- you-contents: full page content extraction
- Security considerations (prompt injection, API key management)

Co-authored-by: factory-droid[bot] <138933559+factory-droid-oss@users.noreply.github.com>

* docs: add You.com MCP search, research, and content extraction guides

Add two documentation pages for integrating You.com's remote MCP server
with crewAI agents:

- search-research/youai-search.mdx: you-search (web/news search)
  and you-research (synthesized cited answers) via DSL or MCPServerAdapter.
  Includes free tier support (100 queries/day, no API key).
- web-scraping/youai-contents.mdx: you-contents (full page content
  extraction) via MCPServerAdapter with schema patching helpers.

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

* fix: add tool_filter to DSL search agent in youai-contents combo example

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

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Co-authored-by: factory-droid[bot] <138933559+factory-droid-oss@users.noreply.github.com>
Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>
Co-authored-by: Lorenze Jay <63378463+lorenzejay@users.noreply.github.com>