fluentd in_tail wrong interval documentation for pos_file_compaction_interval

[juliantaylor]

Describe the bug
The fluentd in_tail source position file compaction documentation implies one can use units like 72h for the configuration but it appeary to strip the unit and use seconds.

https://docs.fluentd.org/input/tail#pos_file_compaction_interval currently has as example:

pos_file_compaction_interval 72h

To Reproduce
for example:

<source>
    @type tail
...
    pos_file_compaction_interval 24h
</source>

will print that it is cleaning up every 24 seconds, not every 24 hours for each configuration:

2020-03-27 08:46:56 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:46:56 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:46:56 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:46:56 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:46:56 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:46:56 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:46:56 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:20 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:20 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:20 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:20 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:20 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:20 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:20 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:44 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:44 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:44 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:44 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:44 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:44 +0000 [info]: #0 Clean up the pos file
2020-03-27 08:47:44 +0000 [info]: #0 Clean up the pos file

Expected behavior
Either the configuration unit is used or the documentation adapted to state it expects seconds as input.

Your Environment

• Fluentd or td-agent version: 1.9.2 td-agent 3.6.0
• Kernel version: uname -r

Your Configuration

see reproduce