docs: fix External LLM Gateways icon

[rajshah4]

Why the icon is missing

The External LLM Gateways page currently sets icon: network. network is a Lucide icon name, but this docs site does not override Mintlify's default Font Awesome icon library. Mintlify therefore cannot resolve that name and leaves a blank icon space in the Enterprise sidebar.

Fix

Use network-wired, the corresponding Font Awesome icon name, so the sidebar icon renders.

Verification

• Confirmed the page frontmatter and the site's docs.json icon configuration.
• Confirmed network-wired exists in Font Awesome and network exists in Lucide.
• git diff --check passed; the Mintlify internal-link check passed.

References: Mintlify icon library setting, Lucide network, Font Awesome network-wired.