Fix support for outputting documentation pages to root output directory

[caendesilva]

Sometimes you just want a documentation site, and nothing else.

Unfortunately, setting output_directory to '' and '/' does not properly load the styles.

[caendesilva]

Caused by DocumentationPage::getCurrentPagePath() which should not include the slash if docsDirectory is empty.

public function getCurrentPagePath(): string
{
    return  Hyde::docsDirectory().'/'.$this->slug;
}

[caendesilva]

• The sidebar header title is still linking to a less nested path. Needs to be fixed.
  Update: fixed, had same root cause. 4b5af09

[caendesilva]

• The "back to home page" button should probably be removed for root documentation pages too.
  Update: The Lagrafo styles currently expect that there is a footer. I'll see about renaming the label instead

Update 2: This does not fall in the 80% use case so I won't add complexity for this edge case at this point in time unless someone requests it.

An easy fix is adding the following CSS:

#lagrafo-app #sidebar #sidebar-navigation {
	height: calc(100vh - 4rem);
}

#lagrafo-app #sidebar #sidebar-footer {
	display: none;
}