First few examples for start of Array.fsi and Seq.fsi

[nhirschey]

This is only a few function examples helping #12124. With multiple people working on array/seq/list examples it seemed like I should submit a pull request for what I had done to minimize duplicated effort and merge conflicts.

I left out list because I saw that @MecuStefan covered the functions here #12134.

@MecuStefan, you are moving faster than me so I will take a step back for now and let you continue from the top down for seq/list/array.

[dnfadmin]

All CLA requirements met.

[nhirschey]

Maintainers--to simplify coordination please feel free to close this pull request in favor of @JYCabello and @MecuStefan's work. Too many people working on the same examples is a great problem : )

This pull request will probably have merge conflicts for seq.fsi with #12133 by @JYCabello.

@JYCabello and @MecuStefan -- Seq/List/Array examples will mostly be the same (#12124 (comment)). I started on Array.fsi expecting to copy over to Seq.fsi and List.fsi once the formatting and examples for Array.fsi were approved. Given that you two have great examples and are moving quickly, I'll stop and leave you to finish the array/seq/list examples.

[dsyme]

Maintainers--to simplify coordination please feel free to close this pull request in favor of @JYCabello and @MecuStefan's work. Too many people working on the same examples is a great problem : )

OK, I'll close this, thanks for simplifying