add --target=wasm32-unknown-unknown to README.md (#2420)
#1564
| Job | Run time |
|---|---|
| 7m 4s | |
| 6m 23s | |
| 6m 1s | |
| 7m 4s | |
| 6m 51s | |
| 5m 48s | |
| 5m 45s | |
| 4m 10s | |
| 3m 13s | |
| 6h 0m 16s | |
| 6h 0m 17s | |
| 2m 59s | |
| 4m 52s | |
| 4m 10s | |
| 4m 16s | |
| 3m 52s | |
| 6m 5s | |
| 0s | |
| 0s | |
| 0s | |
| 0s | |
| 13h 19m 6s |