Add sitemap parameter frontmatter

[h-enk]

Summary

Brief explanation of the feature.

Add parameter

seo:
  title: "" # custom title (optional)
  description: "" # custom description (recommended)
  canonical: "" # custom canonical URL (optional)
  robots: "noindex, nofollow" # custom robot tags (optional)
  sitemap: false # true (default) or false

Update line 5 logic of layouts/sitemap.xml:

{{ printf "<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\"?>" | safeHTML }}
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
  xmlns:xhtml="http://www.w3.org/1999/xhtml">
  {{ range .Data.Pages }}
    {{- if and .Permalink (ne .Params.seo.sitemap false) -}}
..
    {{- end -}}
  {{ end }}
</urlset>
{{/* Based on: https://github.com/gohugoio/hugo/blob/master/tpl/tplimpl/embedded/templates/_default/sitemap.xml */}}

Update docs: Sitemap

Basic example

Include a basic example or links here.

Motivation

Why are we doing this? What use cases does it support? What is the expected outcome?