Suggestion for canonical tag in basic-seo.html

[vtomyev]

instead of:
{{ with .Params.canonical }}

{{ end }} which only works if you set a non empty property for "canonical" property

Use this:
{{ if .Params.canonical.enable }}
{{ with .Params.canonical.link }}

{{ else }}

{{ end }}
{{ end }}

it gives the user a choice wheather or not to have a canonical tag (which by default is the page itself) or to add a URL to another page.