add directory Minix

Minix/1.7.5/MANUALS/CAT2/ISATTY.2

@@ -0,0 +1,13 @@
+SYSTEM CALLS
+    isatty     	- does this descriptor refer to a terminal
+
+INVOCATION
+    int isatty( desc )
+      int desc;
+
+RESULTS
+    1 : <desc> is an open descriptor connected to a terminal.
+    0 : <desc> is not associated with a terminal.
+
+REFERENCES
+    fstat(2), ttyname(3)