Create basic landing page

[spoorcc]

Create a basic landing page for https://dfetch.github.io/

Some basic bootstrap gave me:
https://htmlpreview.github.io/?https://github.com/dfetch-org/dfetch/blob/feature/landing-page/doc/landing.html

[spoorcc]

Deployed first iteration on https://dfetch-org.github.io/