Add use cases page or items into landing page

[moranegg]

Following the Software Citation Principles and the early CodeMeta workshop in 2015, there were some use cases that could clarify the "raison d'être" of CodeMeta.
https://github.com/force11/force11-scwg/blob/master/sc-principles/software-citation-principles.tex

For visitors of the website and newcomers, a list of use cases could be very useful to understand the need for CodeMeta and the current status of the CodeMeta community.

To do so, we need to agree on a set of use cases, directly from the 2016 article or a new enhanced list.

[moranegg]

@codemeta/codemeta-pmc We would like to have on the front page a few use cases for CodeMeta.
Mostly from the first CodeMeta workshop (as captured here: https://codemeta.github.io/use-cases/

We will list here the 3 dominant use-cases that we identified for discussion.

[moranegg]

@lindangulopez