improve linux doc about installdependencies.sh

docs/start/envlinux.md

@@ -26,7 +26,7 @@ Execute ./bin/installdependencies.sh to install any missing Dotnet Core 2.0 depe
 ```
 You can easily correct the problem by execute `./bin/installdependencies.sh`.  
 The `installdependencies.sh` script should install all required dependencies on all supported Linux versions   
-
+> Note: The `installdependencies.sh` script will try to use the default package management mechanism on your Linux flavor (ex. `yum`/`apt-get`/`apt`). You might need to deal with error coming from the package management mechanism related to your setup, like [#1353](https://github.com/Microsoft/vsts-agent/issues/1353)
 
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