also set DOTNET_ROOT environment variable

unsure if this is really needed, but the microsoft docs also mention it

bashrc.d/dotnet.bashrc

@@ -15,5 +15,6 @@ function install_dotnet {
 }
 
 if [ -d "${HOME}/.dotnet" ]; then
-	export PATH=${PATH}:${HOME}/.dotnet:${HOME}/.dotnet/tools
+	export DOTNET_ROOT=${HOME}/.dotnet
+	export PATH=${PATH}:${DOTNET_ROOT}:${DOTNET_ROOT}/tools
 fi