Wrong title for imgAltIsTooLong test

Hi,

The `imgAltIsTooLong` test title needs to be changed as it doesn't fully comply its purpose.

I've proposed change in this pull request.

There is still one thing to do. As I've checked in the translator it seems that `nl` translation should be adjusted too, however I'm not able to give you a reliable translation, so that's something that needs to be done.