Rtc fix

[mwlkhoo]

Update instructions to include details of

• UTC vs local time RTC config in timedatectl
• Verification of clock in-use and i2c-tools

Update scripts such that

• Use UTC instead of local time when updating RTC from system time
• Fix incorrect sleep call
• Allow both ethernet and wifi conn in dhcpcd.exit-hook

Included logging for debugging, but removed in final version of the script. See commit 6c9711ace9a29254c2ebe94575a9ab53d599ef7e