builtin: fix the comments about flushing on print/1 and println/1 (#18927)

Author: kimshrier

vlib/builtin/builtin.c.v

@@ -223,7 +223,7 @@ pub fn flush_stderr() {
 	}
 }
 
-// print prints a message to stdout. Unlike `println` stdout is not automatically flushed.
+// print prints a message to stdout. Note that unlike `eprint`, stdout is not automatically flushed.
 [manualfree]
 pub fn print(s string) {
 	$if android && !termux {
@@ -238,7 +238,7 @@ pub fn print(s string) {
 	}
 }
 
-// println prints a message with a line end, to stdout. stdout is flushed.
+// println prints a message with a line end, to stdout. Note that unlike `eprintln`, stdout is not automatically flushed.
 [manualfree]
 pub fn println(s string) {
 	if s.str == 0 {