docs: Document .continue/configs directory for local config profiles

[continue]

Summary

PR #11935 added support for .continue/configs/ as a third directory for loading local config profiles, alongside .continue/agents/ and .continue/assistants/. This new directory is not documented.

Documentation should:

• Add .continue/configs/ to the list of recognized config directories
• Explain how YAML files in .continue/configs/ are discovered and loaded as local profiles
• Update any directory structure overviews to include this new location

Related PR

• feat: add .continue/configs support #11935 (feat: add .continue/configs support)

Files to Update

• /docs/guides/configuring-models-rules-tools.mdx - mentions .continue/models, .continue/rules, .continue/mcpServers but not .continue/configs
• Any other directory structure documentation