(Do you realize that’s already available in the cog at the R end of the post editor frame?)
1. (With incorrect spaces separating the (square) brackets from the “code” so it shows the markdown format):
[ details=“Summary” ]
Amazingly explained step #1.
[ /details ]
2. (Properly formatted looks like this):
Summary
Amazingly explained step #1.
3. Wait, why does Discourse put “Summary” there when it really means the exact opposite??
4. Let’s try again, replacing “summary” with my own text:
Step 1
Amazingly explained step #1.