clean up Get/SetSlot

document and make arguments consistent

lib/register/instructions/register_transfer.rb

@@ -1,7 +1,14 @@
 module Register
 
-  #transfer the constents of one register to another. possibly called move in some cpus
+  # transfer the constents of one register to another.
+  # possibly called move in some cpus
 
+  # There are other instructions to move data from / to memory, namely GetSlot and SetSlot
+
+  # Get/Set Slot move data around in vm objects, but transfer moves the objects (in the machine)
+  #
+  # Also it is used for moving temorary data
+  
   class RegisterTransfer < Instruction
     def initialize from , to
       @from = wrap_register(from)
@@ -9,4 +16,4 @@ module Register
     end
     attr_reader :from, :to
   end
-end
+end