example.lua: provide a default instance, but don't start it

Provide a default instance in the installation script, but don't
start it.

extra/dist/CMakeLists.txt

@@ -55,7 +55,7 @@ install (FILES tarantoolctl DESTINATION ${CMAKE_INSTALL_BINDIR}
 )
 
 install (FILES example.lua DESTINATION
-        ${CMAKE_INSTALL_SYSCONFDIR}/tarantool/instances.enabled
+        ${CMAKE_INSTALL_SYSCONFDIR}/tarantool/instances.available
     PERMISSIONS
     OWNER_READ OWNER_WRITE OWNER_EXECUTE
     GROUP_READ GROUP_EXECUTE