You need to see documentation again. You can see this cheatsheet
In your case you need to make second line like in example below:
Attempt | #1 | #2 | #3 | #4 | #5 | #6 | #7 | #8 | #9 | #10 | #11
--- | --- | --- | --- |--- |--- |--- |--- |--- |--- |--- |---
Seconds | 301 | 283 | 290 | 286 | 289 | 285 | 287 | 287 | 272 | 276 | 269
difference between this code and your code in repo is that second line with separator has same columns as header. After that this table will be shown