update docs about stdin renaming to cin

README.md

@@ -555,17 +555,18 @@ such as animations.
 
 ## Stdio module
 
-- This module currently defines two global handles (resp. constants): `@stdin` and `@stdout`.
+- This module defines 4 global handles: `@cin`, `@cout`, `@cin_r`, `@cout_r`.
 - You can think of these handles as streams or SFRs (special function registers).
-  To use them, simply load data to or from the handles (e.g. `(ld r0 @stdin)`).
+  To use them, simply load data to or from the handles (e.g. `(ld r0 @cin)`).
 - They operate over unicode code points, which are a superset of ASCII.
+- The "_r" variants work with raw bytes. Do not combine them, or you may get problems with multi-byte characters.
 
 You can use these special handles in almost all instructions:
 
 ```lisp
-(cmp @stdin 'y' 
-    (eq? (ld @stdout '1'))
-    (ne? (ld @stdout '0')))
+(cmp @cin 'y' 
+    (eq? (ld @cout '1'))
+    (ne? (ld @cout '0')))
 ```
 
 When you compile a program using such handles, you will get a strange looking assembly:
@@ -577,7 +578,7 @@ When you compile a program using such handles, you will get a strange looking as
 ```
 
 These are unique constants assigned to the streams at compile time. They are not meant to be used
-directly, but the value can be obtained by simply leaving out the '@' sign: `(ld r0 stdin)`. 
+directly, but the value can be obtained by simply leaving out the '@' sign: `(ld r0 cin)`. 
 That can be useful when these stream handles need to be passed to a function. Obviously this makes
 more sense when there are different kinds of streams available, not just these two default ones.