Use local labels inside functions

See: https://www.nasm.us/xdoc/2.14.02/html/nasmdoc3.html#section-3.9

README.md

@@ -43,9 +43,9 @@ main:
         mov     ebx,0x39
         mov     dword [ebp-4],0x30
 
-schleife:
+.schleife:
         cmp     ebx,dword [ebp-4]
-        je      ende
+        je      .ende
 
         mov     byte [msg+msg_len-3],bl
 
@@ -54,9 +54,9 @@ schleife:
         add     esp,4
 
         dec     ebx
-        jmp     schleife
+        jmp     .schleife
 
-ende:
+.ende:
         add     esp,4
         pop     ebp