Allow configuring of the i_overlay Rayon transitive dep. Document more features.
#3920
| Job | Run time |
|---|---|
| 58s | |
| 2m 0s | |
| 2m 20s | |
| 41s | |
| 1m 59s | |
| 1m 59s | |
| 40s | |
| 29s | |
| 35s | |
| 52s | |
| 27s | |
| 1m 14s | |
| 36s | |
| 48s | |
| 28s | |
| 53s | |
| 1s | |
| 0s | |
| 17m 0s |