Test: force trailing-slash canonical on cli/overview via frontmatter

Temporary probe: verify whether Mintlify emits a per-page `canonical`
override verbatim (including the trailing slash) or normalizes it to
no-slash. On the preview deploy, inspect the rendered
<link rel="canonical"> for /docs/cli/overview/ — if it keeps the slash,
we can script this across all pages; if stripped, drop this commit.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Dgiordano33

cli/overview.mdx

@@ -2,6 +2,7 @@
 title: Checkly CLI
 description: 'Code, test, and deploy synthetic monitoring at scale with the Checkly CLI.'
 sidebarTitle: 'Overview'
+canonical: 'https://www.checklyhq.com/docs/cli/overview/'
 ---
 
 import MainCicdCards from "/snippets/main-cicd-cards.mdx"