Closes #10 add function `create_iso8601()` #39

Job	Run time
Render README	0s
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Documentation	0s
Links / Validate Links	13s
Check / (4.1)	1m 2s
Check / (4.2)	50s
Lint / Lint	1m 5s
Check / (4.3)	1m 9s
Check / (devel)	1m 35s
Code Coverage / Test Coverage	1m 14s
Man Pages / Roxygen	54s
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