add missing extensions

Author: wdpypere

mkdocs/docs/HPC/infrastructure.md

@@ -13,8 +13,8 @@ Science and Innovation (EWI).
 Log in to the HPC-UGent Tier-2 infrastructure via [https://login.hpc.ugent.be](https://login.hpc.ugent.be)
 or using SSH via `login.hpc.ugent.be`.
 
-more info on using the web portal you can find [here](web_portal),
-and about connection with SSH [here](connecting).
+more info on using the web portal you can find [here](web_portal.md),
+and about connection with SSH [here](connecting.md).
 
 ## Tier-2 compute clusters