[DOC] Separated Method#[] from Method#call [Bug #16813] [ci skip]

proc.c

@@ -2271,10 +2271,22 @@ method_clone(VALUE self)
  */
 
 
+/*  Document-method: Method#[]
+ *
+ *  call-seq:
+ *     meth[args, ...]         -> obj
+ *
+ *  Invokes the <i>meth</i> with the specified arguments, returning the
+ *  method's return value, like #call.
+ *
+ *     m = 12.method("+")
+ *     m[3]         #=> 15
+ *     m[20]        #=> 32
+ */
+
 /*
  *  call-seq:
  *     meth.call(args, ...)    -> obj
- *     meth[args, ...]         -> obj
  *
  *  Invokes the <i>meth</i> with the specified arguments, returning the
  *  method's return value.