Add an example user space process

src/app/hello.asm

@@ -0,0 +1,16 @@
+bits 64
+org 0x400000
+
+section .text
+    mov rax, 1
+    mov rdi, 1
+    lea rsi, [rel msg]
+    mov rdx, 14
+    syscall
+
+    mov rax, 60
+    xor rdi, rdi
+    syscall
+
+section .data
+msg: db "Hello, ring 3!", 10

src/app/terminal.c

@@ -270,9 +270,7 @@ void terminal(process_t *p, __attribute__((unused)) uint8_t argc, __attribute__(
 
   proc = p;
 
-  char *greeting = string_format("Welcome to FreywarOS v%s!\n\n", VERSION);
-  WRITE_D(greeting);
-  memory_free(greeting);
+  WRITE_D("Welcome to FreywarOS v" VERSION "!\n\n");
 
   print_prompt();