Clarify the difference between Skipped and Too hard to fix

[tuxayo]

From what I understand:

• skipped tasks are showed again to other contributors and are still in the remaining tasks
• too hard to fix are not showed again and are not in the remaining tasks

If it's correct, then it should be clear that marking as "Too hard to fix" won't let the chance to anyone else to try the task. I fear that it might be used too much instead of "Skip"

For example, we could at least have a confirmation saying:

Are you sure it's too hard to fix? If you think another contributor has a chance to fix it, then skip the task.