Add #[doc(hidden)] to {vga_buffer, serial}::_print functions

blog/content/second-edition/posts/08-hardware-interrupts/index.md

@@ -247,6 +247,7 @@ We can already provoke a deadlock in our kernel. Remember, our `println` macro c
 
 […]
 
+#[doc(hidden)]
 pub fn _print(args: fmt::Arguments) {
     use core::fmt::Write;
     WRITER.lock().write_fmt(args).unwrap();
@@ -302,6 +303,7 @@ To avoid this deadlock, we can disable interrupts as long as the `Mutex` is lock
 
 /// Prints the given formatted string to the VGA text buffer
 /// through the global `WRITER` instance.
+#[doc(hidden)]
 pub fn _print(args: fmt::Arguments) {
     use core::fmt::Write;
     use x86_64::instructions::interrupts;   // new
@@ -322,6 +324,7 @@ We can apply the same change to our serial printing function to ensure that no d
 ```rust
 // in src/serial.rs
 
+#[doc(hidden)]
 pub fn _print(args: ::core::fmt::Arguments) {
     use core::fmt::Write;
     use x86_64::instructions::interrupts;       // new