Fix: update docs about snd

docs/engine/words.md

@@ -5,7 +5,7 @@ Word definitions let you abstract sound design into reusable units.
 ## Defining Sounds
 
 ```forth
-: lead "saw" s 0.3 gain 1200 lpf ;
+: lead "saw" snd 0.3 gain 1200 lpf ;
 ```
 
 Use it with different notes:
@@ -20,8 +20,8 @@ e4 note lead .
 Include the emit to make the word play directly:
 
 ```forth
-: kk "kick" s 1 decay . ;
-: hh "hihat" s 0.5 gain 0.5 decay . ;
+: kk "kick" snd 1 decay . ;
+: hh "hihat" snd 0.5 gain 0.5 decay . ;
 ```
 
 Steps become simple:
@@ -39,5 +39,5 @@ kk
 ```
 
 ```forth
-c4 note saw s dark wet .
+c4 note saw snd dark wet .
 ```