Update examples so they build

I tested all of these and they work.

ctru-rs/examples/buttons.rs

@@ -7,6 +7,7 @@ use ctru::services::hid::{Hid, KeyPad};
 
 fn main() {
     // Setup services
+    ctru::init();
     let apt = Apt::init().unwrap();
     let hid = Hid::init().unwrap();
     let gfx = Gfx::default();

ctru-rs/examples/hello-both-screens.rs

@@ -7,6 +7,7 @@ use ctru::services::hid::{Hid, KeyPad};
 
 fn main() {
     // Initialize services
+    ctru::init();
     let apt = Apt::init().unwrap();
     let hid = Hid::init().unwrap();
     let gfx = Gfx::default();

ctru-rs/examples/hello-world.rs

@@ -9,6 +9,7 @@ fn main() {
     // Initialize ctrulib service handles.
     // Service handles are internally reference-counted. When all instances of a
     // service handle go out of scope, the service will be closed.
+    ctru::init();
 
     // The APT service handles application management functions, such as enabling sleep
     // mode and jumping to the home menu or to other applications

ctru-rs/examples/software-keyboard.rs

@@ -7,6 +7,7 @@ use ctru::services::hid::{Hid, KeyPad};
 use ctru::applets::swkbd::{Swkbd, Button};
 
 fn main() {
+    ctru::init();
     let apt = Apt::init().unwrap();
     let hid = Hid::init().unwrap();
     let gfx = Gfx::default();