Add farmOS Link

[braughtg]

Change the word "farmOS" into a link in the Acknowledgements at the bottom of README.md.

The URL to use for the link is: https://farmos.org/

The "Links" section of the following document shows how to create a link using Markdown:

• https://docs.github.com/en/github/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax

[aidanbennettjones]

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[hughesmac]

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[VPhung1901]

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[hutterfly]

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[anemervontage]

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