Allow numbered figures without caption

[Tom-van-Woudenberg]

Describe the feature you'd like to request

I'd like to have numbered figures without a caption. Now, I can only create a numbered figure with adding a caption. Only a &nbsp leads to an empty caption, but is poorly aligned.

Describe the solution you'd like

• Add the option to the figure directive to add an empty caption.
• Add the option to the image directive to add a number

Describe alternatives you've considered

No response

[Tom-van-Woudenberg]

@douden