Fixed darker footer text color

[applejag]

Change in #77 got a bug.

Well more it's like the footer feature in the footer Docsify plugin is buggy.

The <footer> container element only exists when opening a page initially, but when switching page, SPA-style, the footer content is just embedded into the page without a <footer> element.

Before

Navigating to docs home page	Navigating around and then back to docs home page

After

Navigating to docs home page	Navigating around and then back to docs home page