Mention this repo on the website

[waldyrious]

In the spirit of openness, it seems natural that the very website describing the value of openness and transparency should make it clear that the website itself is open and accessible to improvements.

Currently the only mention I found of this repo was in the "join" page, and only indirectly, i.e. as part of the process to add a new company to the directory, and in the "about" page, again only in passing, as a communication medium.

I suggest adding at least a github icon to the footer, and perhaps even a sentence in the about page mentioning explicitly that the site is maintained openly and collaboratively.