Fix syntax

Signed-off-by: Aaron Erhardt <aaron.erhardt@t-online.de>

Mikrocomputertechnik/asm.md

 ## Load
 
 ```asm
-ldr rd, = const   ; load constant
+ldr rd, =const    ; load constant
 ldr r1, [r0]      ; load content of address of r0 into r1
 ldr r1, [r0, #8]  ; same with offset
 ldr r1, [r0], #8  ; post-increment
@@ -82,8 +82,8 @@ bne LABEL ; not equal         Z = 0
 ## Stack
 
 ```asm
-push r1 ; push r1 on the stack
-pop  r1 ; restore r1 from the stack
+push {r1} ; push r1 on the stack
+pop  {r1} ; restore r1 from the stack
 
 push {r0-r5} ; push r0-r5
 pop  {r0-r5} ; pop r0-r5 (in the correct order)