Split clusters into 3 separate links

mission/index.md

@@ -25,12 +25,11 @@ Other Partners
 
 
 ## Internal structure
-To achieve its goals, HIFIS works in three Competence Clusters which are distributed throughout different Helmholtz research centers, 
-a Cloud Services Cluster (a federated platform for proven first class cloud services), 
-a Backbone Services Cluster (high-performance trusted network infrastructure with unified basic services) and 
-a Software Services Cluster (platform, training and support for high-quality, sustainable software development)
+To achieve its goals, HIFIS works in three Competence Clusters which are distributed throughout different Helmholtz research centers:
+* [Cloud Services](cluster_cloud): Federated platform for proven first class cloud services;
+* [Backbone Services](cluster_backbone): High-performance trusted network infrastructure with unified basic services;
+* [Software Services](cluster_software): Platform, training and support for high-quality, sustainable software development.
 
-See [here](competence_centers) for more detailed description of competence centers.
 
 ## External supervision
 [Governance](governance)