I suggest to rephrase this to better describe what's happening:

* __hostKeyTemplate__: Optional template to dynamically override the format of the Redis key used to lookup a backend

If __hostKeyTemplate__ is not defined, Hipache will do two lookups for each incoming request: one matching exactly the
host header of the HTTP request, another using a '*' + the last two components of this host header (in order to process
wildcards). If __hostKeyTemplate__ is defined, Hipache still does the lookup with the exact host header, but replaces
the second lookup by a dynamic lookup: the __hostKeyTemplate__ parameter is passed through `eval()` and the result
will be used as the key. Note: the `frontend:` is kept at all time.