Wrong documentation for use_aggressive_host_checking

[nook24]

At least for me, it looks like that the documentation of use_aggressive_host_checking is a lie.
From what I learned in naemon/naemon-core#278 this option just swaps the return codes so that a plugin designed for service checks can also be used for host checks.

I scraped real quick through the code and it is just used in one `if``:
https://github.com/naemon/naemon-core/blob/492b8f81af4f57aba69c154881730b5843835647/src/naemon/checks_host.c#L507-L508

The documentation is talking about performance impacts and other things that just looks total wrong to me.
https://www.naemon.io/documentation/usersguide/tuning.html#avoid_aggressive_host_checking
https://www.naemon.io/documentation/usersguide/configmain.html#use_agressive_host_checking

If you guys agree, I will send a pull request to fix this.

[sni]

Sure, please send a PR to clarify this option.