Remove references to the empty halo2 crate from the README
#4034
| Job | Run time |
|---|---|
| 21m 50s | |
| 3m 33s | |
| 1m 34s | |
| 3m 22s | |
| 3m 5s | |
| 3m 15s | |
| 13s | |
| 15m 35s | |
| 9m 4s | |
| 14m 46s | |
| 11m 45s | |
| 16m 46s | |
| 16m 41s | |
| 9m 6s | |
| 11m 50s | |
| 10m 39s | |
| 9m 58s | |
| 13m 9s | |
| 16m 16s | |
| 3h 12m 27s |