Add explanation of tuple deconstruction syntax in F# Tour

[Copilot]

Summary

Fixes #9c06c3d5 (the issue about the last tuple sample being challenging for newcomers)

The F# Tour documentation included a code sample that used pattern matching/deconstruction syntax in function parameters without any prior introduction or explanation. Specifically, the sample showed:

let convertFromStructTuple (struct(a, b)) = (a, b)

This syntax (struct(a, b)) deconstructs a struct tuple in the function parameter, but readers encountering this for the first time might not understand what's happening, especially since the F# Tour is often one of the first pages people read when exploring F#.

Changes

Added a brief explanation immediately after the struct tuple code sample that:

• Clarifies that the sample demonstrates pattern matching to deconstruct tuples in function parameters
• Provides the specific example (struct(a, b)) that appears in the code
• Explains what it does (extracts the individual elements)
• References the detailed Tuples documentation for readers who want to learn more

Impact

This minimal change makes the F# Tour more accessible to beginners by providing context for advanced syntax when it's first encountered, while keeping the tour concise by referencing more detailed documentation rather than explaining everything inline.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Last tuple sample challenging</issue_title>
<issue_description>
The last tuple sample uses deconstruction which has not been introduced on this page, and this page can easily be one of the first pages someone exploring from C# sees.

Suggest either referencing another article or introducing or at least mentioning deconstruction.

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Document Details

⚠ Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.

• ID: 89bef555-3de1-5d81-c02b-2ac8c049423b
• Version Independent ID: eb13ad9e-2c95-979b-6d6e-13d29653c6ba
• Content: Tour of F#
• Content Source: docs/fsharp/tour.md
• Product: dotnet-fsharp
• GitHub Login: @cartermp
• Microsoft Alias: phcart</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #25072

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Internal previews

📄 File	🔗 Preview link
docs/fsharp/tour.md	Tour of F#

[BillWagner]

This is ready for final review, once I take my suggestion.

[Copilot]

Pull Request Overview

This PR addresses accessibility concerns in the F# Tour documentation by adding clarification for tuple deconstruction syntax that was previously unexplained. The change helps newcomers understand an advanced F# feature when they first encounter it.

• Adds explanation for tuple deconstruction/pattern matching syntax in function parameters
• References detailed Tuples documentation for further learning
• Improves accessibility for developers new to F# without disrupting the tour's flow