Core and Enterprise: get-started write examples

[jstirnaman]

• Fix <https://docs.influxdata.com/influxdb3/core/get-started/#example-write-data-using-the-influxdb3-cli|this example of writing using the CLI> hanging continuation (reported by @stuartcarnie) Incomplete influxdb3 CLI example for writing #5993
• Add stdin examples
• Add/fix placeholder notes (TOKEN, DATABASE_NAME)
• Finish codeblock test setup for Core and Enterprise

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