[R] [Doc] Write a longer form documentation for the lubridate functionality

[asfimport]

Write a detailed documentation of the lubridate bindings currently available in the arrow R package.

Reporter: Dragoș Moldovan-Grünfeld / @dragosmg

_{Note: This issue was originally created as ARROW-16397. Please see the migration documentation for further details.}

[asfimport]

Apache Arrow JIRA Bot:
This issue was last updated over 90 days ago, which may be an indication it is no longer being actively worked. To better reflect the current state, the issue is being unassigned per project policy. Please feel free to re-take assignment of the issue if it is being actively worked, or if you plan to start that work soon.

[asfimport]

Nicola Crane / @thisisnic:
Closing this for now as the new package documentation in ARROW-15011 shows us what we have implemented, and we can reopen this or open a new ticket if we decide we need something more detailed. (and it's a duplicate of ARROW-16319)