Add canonicalUrl parameter to front matter

[scambelo]

Hi!

✨ I would like to add a new parameter canonicalUrl to front matter that set a different canonical URL.

Right now the default behaviour is to set the <link rel="canonical"> tag to the permalink of the page, which is fine in most of the cases, but sometimes I have to publish in other blogs (i.e. company blog) and I like to cross-post in my own site without affecting SEO. With this new feature it is possible to set a custom canonical URL when needed just by adding the parameter canonicalUrl to the front matter of the page.

The change consist in modify the file layouts/partials/head.html from this:

  <link rel="canonical" href="{{ .Permalink }}" />

To this:

  {{ if .Params.canonicalUrl }}
  <link rel="canonical" href="{{ .Params.canonicalUrl }}" />
  {{ else }}
  <link rel="canonical" href="{{ .Permalink }}" />
  {{ end }}

I have tested the change and works as expected. If the feature is approved I could do a PR.

Thanks!