message: update AssemblyLevel documentation.
diff: @@ -30,9 +30,10 @@ namespace mfem
  enum class AssemblyLevel
  {
  /// Legacy fully assembled form, i.e. a global sparse matrix in MFEM,
  - /// Hypre or PETSC format.
  + /// Hypre or PETSC format, the assembly is ALWAYS done on the host.
  LEGACYFULL = 0,
  /// Fully assembled form, i.e. a global sparse matrix in MFEM format.
  + /// The assembly is compatible with device execution.
  FULL,
  /// Form assembled at element level, which computes and stores dense element
  /// matrices.
  