Add external links to sub navigation menu

[evandrosaturnino]

Description

Add external links to the sub navigation menu - Needed initially to include tBTCScan external link.

• [x] add external links to sub navigation menu
• [x] add tbtcscan link to tbtc sub navigation menu

Type of change

• [x] 💅 New Feature (Breaking/Non-breaking Change)
• [ ] 🐛 Bug fix (Non-breaking Change: Fixes an issue)
• [ ] 🛠️ Chore (Non-breaking Change: Doc updates, pkg upgrades, typos, etc..

Notice

• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Issue (if applicable)

closes https://github.com/threshold-network/token-dashboard/issues/776

Screenshots (if applicable)

Pull Request Type

• [x] New Feature (Breaking/Non-breaking Change)

[github-actions[bot]]

Preview uploaded to https://preview.dashboard.test.threshold.network/add-external-links-to-sub-navigation-menu/index.html.

[somaweb3]

Thanks for the tbtcscan redirect, the changes look good.

[github-actions[bot]]

Preview uploaded to https://preview.dashboard.test.threshold.network/add-external-links-to-sub-navigation-menu/index.html.

[github-actions[bot]]

Preview uploaded to https://preview.dashboard.test.threshold.network/add-external-links-to-sub-navigation-menu/index.html.