Rename "Downtime" tab to "Unsigned Blocks" for validator addresses #728

All 2 567 tests pass, 74 skipped in 3m 32s

      6 files ±0   366 suites ±0 3m 32s ⏱️ +4s
2 641 tests ±0 2 567 ✔️ +1 74 💤 ±0 0 ❌ - 1
2 655 runs ±0 2 579 ✔️ +1 76 💤 ±0 0 ❌ - 1

Results for commit 4deba2f. ± Comparison against earlier commit 27ebc0d.