split: Add more examples

[gasi]

Description of the change

This change adds more examples to the String.split function and fixes a typo (occurences → occurrences).

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Checklist:

• [x] Added the change to the changelog's "Unreleased" section with a reference to this PR (e.g. "- Made a change (#0000)")
• [ ] Linked any existing issues or proposals that this pull request should close
• [x] Updated or added relevant documentation
• [x] Added a test for the contribution (if applicable)

[michaelficarra]

If you want more examples, you can add

• adjacent matches:

split (Pattern "b") "abbc" == ["a", "", "c"]

• overlapping matches:

split (Pattern "bb") "abbbc" == ["a", "bc"]