Mention that experimental lines should be used only in addition to the main ones

content/apt/apt-1/contents.lr

@@ -29,7 +29,7 @@ To enable all package managers using the libapt-pkg library to access metadata a
    deb-src https://deb.torproject.org/torproject.org <DISTRIBUTION> main
    ```
 
-If you want to try experimental packages:
+If you want to try experimental packages, add these **in addition** to the lines from above (Note, use whatever is the current experimental version instead of 0.4.5.x from the example below):
 
    ```
    deb     https://deb.torproject.org/torproject.org tor-experimental-0.4.5.x-<DISTRIBUTION> main