feat: add guessing example

examples/guessing.ltor

@@ -0,0 +1,23 @@
+set i to 0
+set toGuess to random_int(0, 100)
+while 1 do
+    set guessed to input_number()
+    if i > 20 then
+        # do you really want to continue?
+        break
+    end
+    if guessed = toGuess then
+        # success
+        print_ascii(83)
+        break
+    end
+    if guessed < toGuess then
+        # too low
+        print_ascii(76)
+    end
+    if guessed > toGuess then
+        # too high
+        print_ascii(72)
+    end
+    set i to i+1
+end