Added a README

examples/EAGLE_25/README

+ICs extracted from the EAGLE suite of simulations. 
+
+The particle distribution here is the snapshot 27 (z=0.1) of the 25Mpc
+Ref-model. h- and a- factors from the original Gadget code have been
+corrected for. Variables not used in a pure hydro & gravity code have
+been removed. 
+Everything is ready to be run without cosmological integration. 
+
+The particle load of the main EAGLE simulation can be reproduced by
+running these ICs on 64 cores.