Merge branch 'refs-to-hirse-ps' into 'master'

Add references to hirse_ps

See merge request !676

_layouts/partners.html

@@ -44,7 +44,9 @@
                         <img src="{% link assets/img/third-party-logos/Helmholtz_Leadership_Academy_2017_Helmholtz_Logo_RGB_untereinander_EN.svg %}" alt="Helmholtz Leadership Academy Logo">
                     </a>
 
-
+                    <a href="https://www.helmholtz-hirse.de/" class="btn btn-light btn-lg btn-logo">
+                        <img src="{% link assets/img/third-party-logos/hirse_ps.svg %}" alt="Logo of HiRSE_PS - Helmholtz Platform for Research Software Engineering - preparatory study">
+                    </a>
                 </div>
 
                 <h1>National & International Partners</h1>