Copy docs into Zeek repo directly

This is based on commit 2731def9159247e6da8a3191783c89683363689c from the
zeek-docs repo.

doc/scripting/framework_logging_factorial_01.zeek

@@ -0,0 +1,19 @@
+module Factor;
+
+function factorial(n: count): count
+    {
+    if ( n == 0 )
+        return 1;
+    else
+        return ( n * factorial(n - 1) );
+    }
+
+event zeek_init()
+    {
+    local numbers: vector of count = vector(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
+    
+    for ( n in numbers )
+        print fmt("%d", factorial(numbers[n]));
+    }
+
+