Declutter by removing duplicate link in the same footer section

[Ainali]

As identified in publiccodenet/about#1105 in the footer.liquid we generate a link to the repository twice in the "GitHub repository information" section. I suggest we remove <li><a href="{{ site.github.repository_url }}">Content and code</a></li> and just have the link that is explained with a sentence left (<a href="{{ site.github.repository_url }}">{{ site.github.repository_nwo }}</a>).

[ElenaFdR]

As mentioned in #55, @angelplasma and I had planned to get rid of footer.liquid everywhere; we've already done this on pubbliccode.net. Since it doesn't seem like that's broken anything, I propose we get rid of it everywhere now.

[ElenaFdR]

I still propose we get rid of all 3 bullets, as experienced users will navigate via the universal nav or footer and novice users will be invited by the 'edit this page' buttons in the right nav.

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