docs/FAQ.md: answer monitoring `jj log` with watch and TUIs #398

Job	Run time
Build binary artifacts (linux-x86_64-musl)	4m 56s
Build binary artifacts (linux-x86_64-gnu)	5m 9s
Build binary artifacts (linux-aarch64-musl)	5m 33s
Build binary artifacts (linux-aarch64-gnu)	6m 32s
Build binary artifacts (macos-x86_64)	14m 16s
Build binary artifacts (macos-aarch64)	5m 15s
Build binary artifacts (win-x86_64)	7m 54s
	49m 35s

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