container: improve documentation

This change removes inconsistencies collected over time in this package.

Signed-off-by: Ophestra <cat@gensokyo.uk>

container/initremount.go

@@ -9,7 +9,7 @@ import (
 
 func init() { gob.Register(new(RemountOp)) }
 
-// Remount appends an [Op] that applies [RemountOp.Flags] on container path [RemountOp.Target].
+// Remount is a helper for appending [RemountOp] to [Ops].
 func (f *Ops) Remount(target *check.Absolute, flags uintptr) *Ops {
 	*f = append(*f, &RemountOp{target, flags})
 	return f