fix comments typos

s/propogated/propagated

Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>

builder/parser/parser.go

@@ -42,7 +42,7 @@ func init() {
 	// The command is parsed and mapped to the line parser. The line parser
 	// recieves the arguments but not the command, and returns an AST after
 	// reformulating the arguments according to the rules in the parser
-	// functions. Errors are propogated up by Parse() and the resulting AST can
+	// functions. Errors are propagated up by Parse() and the resulting AST can
 	// be incorporated directly into the existing AST as a next.
 	dispatch = map[string]func(string) (*Node, map[string]bool, error){
 		"user":       parseString,