WIP: updating time examples to use doubles / ints.

[ChrisBarker-NOAA]

See Discussion: https://github.com/orgs/cf-convention/discussions/383

I think the consensus on that discussion was to:

[x] Change the float time examples to double
and
[x] Change some of the double examples to an integer type.

I've done the first one -- more to follow.

Release checklist

• Authors updated in cf-conventions.adoc? Add in two places: on line 3 and under .Additional Authors in About the authors.
• Next version in cf-conventions.adoc up to date? Versioning inspired by SemVer.
• history.adoc up to date?
• Conformance document up to date? (no impact)

For maintainers

After the merge remember to delete the source branch.
Tags are set at the conclusion of the annual meeting; until then, main always is a draft for the next version.

[ChrisBarker-NOAA]

OK -- I've now changed all float times to double.

And I changed a number of the other examples to integer types. I tried to pick types, and units, that are appropriate to the data.

It's all pretty arbitrary, but I think it's better that there be a variety of examples.

Feedback welcome if you have any better ideas on what units should be used in any particular case.