container: improve documentation

This change removes inconsistencies collected over time in this package.

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

container/check/overlay.go

@@ -11,7 +11,8 @@ const (
 	SpecialOverlayPath = ":"
 )
 
-// EscapeOverlayDataSegment escapes a string for formatting into the data argument of an overlay mount call.
+// EscapeOverlayDataSegment escapes a string for formatting into the data
+// argument of an overlay mount system call.
 func EscapeOverlayDataSegment(s string) string {
 	if s == "" {
 		return ""