os: add info about overwritten content to `write_file` (#14109)

vlib/os/os.v

@@ -367,7 +367,8 @@ pub fn expand_tilde_to_home(path string) string {
 	return path
 }
 
-// write_file writes `text` data to a file in `path`.
+// write_file writes `text` data to the file in `path`.
+// If `path` exists already, the contents of `path` will be overwritten with the contents of `text`.
 pub fn write_file(path string, text string) ? {
 	mut f := create(path) ?
 	unsafe { f.write_full_buffer(text.str, usize(text.len)) ? }