[tor-relays] [WARN]Failing because we have 4063 connections already. Please read doc/TUNING for guidance

[tor-admin at torland.me]

Hi all,

since I upgraded the torland relay from 2.6.7 to 0.2.7.6 I get the following 
warnings:

09:20:30 [WARN] Failing because we have 4063 connections already. Please read 
doc/TUNING for guidance. [101144347 similar message(s) suppressed in last 
21600 seconds]

Google only spits out https://trac.torproject.org/projects/tor/ticket/16929 
which does not help me. I don't find the mentioned branch bug16929 in git.

Can someone please advise what has to be done to avoid the warning, or point 
me where I find can the file "doc/TUNING". 

Thanks

torland