Allow modification of header metadata tags

[TWinsnes]

All the metadata fields are currently hard-coded in the head.html partial

lotusdocs/layouts/partials/head.html

Lines 8 to 13 in 7f034c9

	<meta name="description" content="A Lightweight, Modern Documentation Theme for Hugo" />
	<meta name="keywords" content="Documentation, Hugo, Hugo Theme, Bootstrap" />
	<meta name="author" content="Colin Wilson - Lotus Labs" />
	<meta name="email" content="support@aigis.uk" />
	<meta name="website" content="https://lotusdocs.dev" />
	<meta name="Version" content="v0.1.0" />

It would be great to be able to modify these from the site config, or even use the information in the front matter of individual docs pages. The metadata tags like description and author are used by services to display additional information about links, and ideally it should represent the page it links to.

[TWinsnes]

I've created a pull request that implements this change
#254