Add link to srobo/ansible to README

[sedders123]

Provide link + explanation of location of nginx config so people can find to add redirects if necessary.

[PeterJCLaw]

Redirects are a difficult one -- we should consider that there's a lot of benefit to having everything pertaining to the website in one repo. In that regard, https://github.com/jekyll/jekyll-redirect-from (which is available to us in GitHub Pages) is perhaps a better solution. (Though it is a slightly less great UX).

[sedders123]

This was more for redirects to external resources e.g. srobo/ansible#10 agree we can use Jekyll for redirects of individual pages on this site

[sedders123]

Alternatively rather than linking to the repo for redirects maybe we could add a section on how the site is deployed (which would link to the repo) so people can discover the nginx config that way.