[TOSprint] Link to Booking System OSGeo CodeSprint 2018 in WIKI

[Till Adams]

Dear OSGeo-Community,

this is just a reminder, I put the official link to the hotel booking
system for the OSgeo CodeSprint 03/2018 in Bonn on the WIKI page:

https://wiki.osgeo.org/wiki/OSGeo_Code_Sprint_2018#Accommodations

Please make sure to save jup your caravan as soon as possible. We will
open the same booking system with opening of bookings of the FOSSGIS
conference within the next days. This may lead to a fast book-out of
BaseCamp!

Till