[FEAT] More flexible syntax for making cards

Is your feature request related to a problem? Please describe.
I use callouts within pages to define certain terms eg.

> [!define] Clausius–Clapeyron relation
> **The temperature dependence of pressure at a phase matter boundary.**
> This results in a 7% increase in water holding capacity of the atmosphere for each additional 1°C increase in temperature.

It would be nice if this could be picked up as a flash card.

Describe the solution you'd like
Instead of defining a separator between the question and answer, define a regex with two capture groups (one for the question and one for the answer). This would allow people a lot of flexibility in how they integrate flashcards into surrounding content.

In the settings page, the default could be changed to a regex without changing the default behavior. eg. separator for inline flashcards: :: would become separator for inline flashcards: (.*)::(.*)

Additional context
I feel like this would allow cards to be more seamlessly integrated into the broader flow of the page, rather that sticking out from the surrounding context due to the syntax.