Why? Reduce the wall time during which the system believes it's 1970. Makes syslog timestamps more sensible.
Rationale: saves ~16.6MiB of RSS and mildly simplifies the operating conditions of a gokrazy appliance. Before: `892.4 MiB total, 808.1 MiB available` After: `892.4 MiB total, 824.7 MiB available` (cf. https://github.com/gokrazy/gokrazy/discussions/354#discussioncomment-15421711)
Migrated advice from https://github.com/gokrazy/gokrazy/discussions/352#discussioncomment-15404080 to the docs.