fix(docs): broken /apps/introduction/overview link in verify-social-accounts guide

[ygd58]

Bug

docs/base-account/guides/verify-social-accounts.mdx line 435 links to /apps/introduction/overview which returns 404 on the live site.

Steps to reproduce:

1. Visit https://docs.base.org/base-account/guides/verify-social-accounts
2. Scroll to the end — click 'Apps overview' link
3. Gets 404

Root cause:
docs/apps/introduction/overview.mdx has hidden: true in frontmatter so it is not publicly accessible.

Fix:
Replace /apps/introduction/overview with /apps which returns 200.

Affected file:
docs/base-account/guides/verify-social-accounts.mdx line 435