Add multilingual Agila learning examples and Git practice guide

tl/ada-contracts-and-review/main.adb

@@ -0,0 +1,18 @@
+pragma Assertion_Policy (Check);
+with Ada.Text_IO;
+
+procedure Main is
+   subtype Level is Integer range 0 .. 10;
+   function Next_Level (Current : Level) return Level
+     with Pre => Current < Level'Last,
+          Post => Next_Level'Result = Current + 1;
+
+   function Next_Level (Current : Level) return Level is
+   begin
+      return Current + 1;
+   end Next_Level;
+begin
+   pragma Assert (Next_Level (0) = 1);
+   pragma Assert (Next_Level (9) = 10);
+   Ada.Text_IO.Put_Line ("Pumasa ang dalawang pagsusuri sa hangganan");
+end Main;