message: Add explanatory text to branch-history
diff: my $branch_max_commits = 100;
  my $commit_max_files_changed = 100;
  -my $max_blob_kb = 200;
  +my $max_blob_kb = 1;
  my $max_commit_kb = 400;
  my $max_branch_kb = 1000;
  @@ -89,4 +89,25 @@ if ($total_size > $max_branch_kb*1024) {
  $status = 1;
  }
  +if ($status) {
  + print <<EOF
  +
  +The failure of this script indicate that large files or a large number of files
  +have been added or committed in the current branch history.
  +
  +This could be OK in certain cases, but it could also be a sign that large files
  +have accidentally been committed.
  +
  +To address this error, examine the listed files and commits to make sure all
  +large changes were intentional. If there is a wrong commit that has to be
  +deleted, please either:
  +
  +1) Recreate the branch without that commit.
  +2) Indicate that the branch should be squash-merged
  +
  +or contact a member of the MFEM team for help or if you have questions.
  +
  +EOF
  +}
  +
  exit $status;
  