[SEC-32636] docs(mcp): add IoC Explorer tools to MCP Server tools page

[paul-ber]

What does this PR do?

Adds documentation for the 4 IoC Explorer MCP tools to the MCP Server tools page under the Security section.

Motivation

SEC-32636 / parent SEC-32051 (IoC Explorer MCP tools).

Additional notes

4 tools added (all in the security toolset):

Tool	Permissions
get_datadog_ioc_filter_values	Security Signals Read
get_datadog_ioc_indicator	Security Signals Read
list_datadog_ioc_indicators	Security Signals Read
triage_datadog_ioc_indicator	Security Signals Write

Placement: Security section, after signals triage tools, before detection rules — consistent with feature grouping and shared permissions.

Link: Added [64] reference to the existing IoC Explorer docs page.

Permission strings: Verified against defs/permissions.go DisplayName fields (Security Signals Read / Security Signals Write).

Descriptions: Derived from the Go tool definitions in dd-source.

[github-actions]

Preview links (active after the build_preview check completes)

Modified Files

• https://docs-staging.datadoghq.com/paul.berthelot/SEC-32636/ioc-explorer-mcp-docs/mcp_server/tools