[unpackfs] Expand documentation

- comment out the squashfs example, since it's not readily
   available even on developer systems
 - add entries for the upcoming "file" type.

src/modules/unpackfs/unpackfs.conf

@@ -9,13 +9,18 @@
 #       target dir relative to rootMountPoint.
 
 ---
-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 it)
+#   sourcefs: the type of the source files; valid entries are
+#       - *ext4* (copies the filesystem contents)
+#       - *squashfs* (unsquashes)
+#       - *file* (copies a file or directory)
+#       - (may be others if mount supports it)
 #   destination: path relative to rootMountPoint (so in the target
 #       system) where this filesystem is unpacked.
+unpack:
 
 # Usually you list a filesystem image to unpack; you can use
 # squashfs or an ext4 image.
@@ -33,6 +38,14 @@ unpack:
 
 # 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
+#    -   source: ./example.sqfs
-        sourcefs: squashfs
+#        sourcefs: squashfs
-        destination: ""
+#        destination: ""
+# You can list individual files
+    -   source: ../CHANGES
+        sourcefs: file
+        destination: "/tmp/derp"
+# .. or directories
+    -   source: ../src/modules/dummycpp
+        sourcefs: file
+        destination: "/tmp/derp"