doc: add instructions to build with ninja #1465
| Job | Run time |
|---|---|
| 18m 30s | |
| 18m 55s | |
| 20m 17s | |
| 13m 42s | |
| 13m 39s | |
| 18m 31s | |
| 13m 51s | |
| 18m 19s | |
| 13m 51s | |
| 14m 56s | |
| 19m 16s | |
| 19m 3s | |
| 13m 8s | |
| 17m 19s | |
| 13m 30s | |
| 18m 48s | |
| 19m 28s | |
| 20m 25s | |
| 18m 47s | |
| 20m 3s | |
| 21m 1s | |
| 19m 55s | |
| 13m 59s | |
| 16m 58s | |
| 6h 56m 11s |