Thank you very much for your quick answer!
The second solution could do the trick, but it would be to complicated to create a page each time we add a gallery, so I prefer not to use this one.
The first solution is actually not really what I want, but it goes in the right direction. Wouldn’t it be possible to add a setting that would allow to display or not the name of the album just before the galleries, when using the shortcode [album=x] ?
Of course I may use your first solution to display the gallery description on the gallery page, but still I wouldn’t be able to display anything on the albums page, because it would appear on the gallery page.
If you think of a solution that needs to do some modifications directly in the code, then there is no problem for me to implement it.
Thank you,
Romain