Update unpackfs.conf examples and documentation

src/modules/unpackfs/unpackfs.conf

@@ -13,12 +13,26 @@ unpack:
 # Each list item is unpacked, in order, to the target system.
 # Each list item has the following attributes:
 #   source: path relative to the live / intstalling system to the image
-#   sourcefs: ext4 or squashfs (may be others if mount supports is)
+#   sourcefs: ext4 or squashfs (may be others if mount supports it)
 #   destination: path relative to rootMountPoint (so in the target
 #       system) where this filesystem is unpacked.
-    -   source: "/path/to/filesystem.img"
-        sourcefs: "ext4"
-        destination: ""
-    -   source: "/path/to/another/filesystem.sqfs"
-        sourcefs: "squashfs"
+
+# Usually you list a filesystem image to unpack; you can use
+# squashfs or an ext4 image.
+#
+#   -   source: "/path/to/filesystem.sqfs"
+#       sourcefs: "squashfs"
+#       destination: ""
+
+# You can list more than one filesystem.
+#
+#   -   source: "/path/to/another/filesystem.img"
+#       sourcefs: "ext4"
+#       destination: ""
+#
+
+# You can list filesystem source paths relative to the Calamares run
+# directory, if you use -d (this is only useful for testing, though).
+    -   source: ./example.sqfs
+        sourcefs: squashfs
         destination: ""