Update ubuntu-lts.md

docs/Getting Started/Getting Started Guides/Install/ubuntu-lts.md

@@ -15,6 +15,8 @@ This is quite easy as everything is available as packages.
 
 Just type:
 ```bash
+sudo apt update
+sudo apt install devscripts equivs
 export CAMITK_LATEST="4.1.2"
 workingDir=$(mktemp --tmpdir -d camitk-$CAMITK_LATEST-build-tmp.XXX)
 cd $workingDir