README.riscos: Improve the document
#12992
| Job | Run time |
|---|---|
| 11m 3s | |
| 12s | |
| 15m 40s | |
| 14m 58s | |
| 17m 47s | |
| 34m 40s | |
| 10m 26s | |
| 9m 23s | |
| 34m 10s | |
| 11m 21s | |
| 3m 39s | |
| 51m 38s | |
| 9m 46s | |
| 21m 8s | |
| 2m 45s | |
| 9m 51s | |
| 22m 41s | |
| 2m 47s | |
| 22m 33s | |
| 2m 21s | |
| 9m 36s | |
| 2m 18s | |
| 9m 29s | |
| 6m 58s | |
| 9m 3s | |
| 9m 51s | |
| 8m 17s | |
| 23m 38s | |
| 9m 11s | |
| 6h 37m 10s |