Document an example of using FeoBlog with an HTTP proxy.

[NfNitLoop]

I should document and test an minimal example.

I'm using Apache with LetsEncrypt, and ProxyPass like:

    # Proxy all traffic to the local server:
    ProxyPass "/" "http://127.0.0.1:8080/"

... though, I just found out that the DEFLATE filter is post-processing files that pass through my proxy and messing up its ETags. So, seems worth documenting. See also:

#68