message: Update check-1st-ti.cpp
diff: // Check timeintegrator Miniapp:
  // ----------------------------------------------------------------
  //
  -//
  // Compile with: make check-timeintegrator
  //
  // Sample runs: check-timeintegrator
  using namespace std;
  using namespace mfem;
  -
  /** Class for simple linear first order ODE.
  *
  * du/dt + a u = 0
  