update docs

docs/_docs/server_installation.md

@@ -44,6 +44,7 @@ sudo apt-get install default-jdk
 java -version
 
 # install library connection GDAL to Java
+# If libgdal-java is not available for your os, you need to insert libgdal-java manually, see wiki below.
 sudo apt install libgdal-java
 
 # copy zip-archiv to a new folder
@@ -66,6 +67,8 @@ chmod +x *.sh
 
 Consult the [RSDB wiki](https://github.com/environmentalinformatics-marburg/rsdb/wiki/Troubleshooting) if you encounter issues.
 
+If libgdal-java is not available for your os, see in wiki: [Unable to locate package libgdal-java](https://github.com/environmentalinformatics-marburg/rsdb/wiki/Troubleshooting#unable-to-locate-package-libgdal-java)
+
 ## Other Linux distributions
 
 You may translate instructions of RSDB installation to other Linux distribution commands.