Add Stdin.isRaw.

doc/site/modules/io/stdin.markdown

@@ -4,6 +4,18 @@ The standard input stream.
 
 ## Static Methods
 
+### **isRaw**
+
+Returns `true` if stdin is in raw mode. When in raw mode, input is not echoed
+or buffered, and all characters, even non-printing and control characters go
+into stdin.
+
+Defaults to `false`.
+
+### **isRaw**=(value)
+
+Sets raw mode on or off.
+
 ### **readByte**()
 
 Reads one byte of input from stdin. Blocks the current fiber until a byte has