fix: correct typo in og:url meta tag (pdov.dev → pdoc.dev)

[TejasAmle]

What

The og:url Open Graph meta tag on the pdoc homepage has a typo: pdov.dev instead of pdoc.dev.

<!-- Before (line 9 of docs/index.html.jinja2) -->
<meta property="og:url" content="https://pdov.dev/">

<!-- After -->
<meta property="og:url" content="https://pdoc.dev/">

Why this matters

The og:url meta tag is used by social media platforms (Twitter/X, LinkedIn, Facebook, Slack, etc.) to canonicalise shared links. With the wrong URL, shares of the pdoc homepage could resolve to a non-existent domain rather than back to https://pdoc.dev/.

The other three pdoc.dev references on the same page (og:image, thumbnailUrl, image) are already correct — only the og:url has the transposed c/v.

How verified

Confirmed the typo in docs/index.html.jinja2 line 9, compared against all other pdoc.dev references in the file which are correct.