doc(README): add logo and acknowledgement

Refs #43

README.md

-# airGRiwrm: airGR based Integrated Water Resource Management R package
+# airGRiwrm: airGR based Integrated Water Resource Management R package <img src="man/figures/logo.png" align="right" height="80px"/>
 
 **airGRiwrm** is an extension of the **airGR** R package for managing semi-distributive hydrological model on an anthropized catchment.
 
@@ -22,3 +22,9 @@ remotes::install_gitlab("in-wop/airGRiwrm", host = "gitlab.irstea.fr", dependenc
 ## Get started
 
 Visit the website dedicated to the package at https://airgriwrm.g-eau.fr for tutorials, usage examples and documentation.
+
+## Acknowledgement
+
+The authors would like to thank the European Commission and the French National Research Agency (ANR) for funding in the frame of the collaborative  international consortium [IN-WOP](http://www.waterjpi.eu/joint-calls/joint-call-2018-waterworks-2017/booklet/in-wop) financed under the 2018 Joint call of the WaterWorks2017 ERA-NET Cofund. This ERA-NET is an integral part of the activities developed by the Water JPI.
+
+<div style="display: flex; justify-content: space-between;">![Water JPI](man/figures/logo_water_jpi.png) ![Water Works 2017](man/figures/logo_water_works_2017.png) ![European Commission](man/figures/logo_european_commission.jpg) ![2018 Joint call](man/figures/logo_2018_joint_call.png)</div>
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