Add documentation for exported functions and types

Signed-off-by: Jamie Hannaford <jamie.hannaford@rackspace.com>

mount/mountinfo.go

@@ -1,7 +1,40 @@
 package mount
 
+// MountInfo reveals information about a particular mounted filesystem. This
+// struct is populated from the content in the /proc/<pid>/mountinfo file.
 type MountInfo struct {
-	Id, Parent, Major, Minor         int
-	Root, Mountpoint, Opts, Optional string
-	Fstype, Source, VfsOpts          string
+	// Id is a unique identifier of the mount (may be reused after umount).
+	Id int
+
+	// Parent indicates the ID of the mount parent (or of self for the top of the
+	// mount tree).
+	Parent int
+
+	// Major indicates one half of the device ID which identifies the device class.
+	Major int
+
+	// Minor indicates one half of the device ID which identifies a specific
+	// instance of device.
+	Minor int
+
+	// Root of the mount within the filesystem.
+	Root string
+
+	// Mountpoint indicates the mount point relative to the process's root.
+	Mountpoint string
+
+	// Opts represents mount-specific options.
+	Opts string
+
+	// Optional represents optional fields.
+	Optional string
+
+	// Fstype indicates the type of filesystem, such as EXT3.
+	Fstype string
+
+	// Source indicates filesystem specific information or "none".
+	Source string
+
+	// VfsOpts represents per super block options.
+	VfsOpts string
 }