Add guidance for searching multi-line function call chains in Copilot instructions

[Copilot]

• Review current copilot-instructions.md file structure
• Add guidance section about searching for function call chains
• Provide examples of multi-line Rust method chaining patterns
• Suggest using ripgrep with multi-line search or AST-based tools
• Condense guidance to reduce token count per feedback
• Add rustfmt to cspell.json word list

Summary

Updated the Copilot instructions with concise guidance about searching for multi-line function call chains in Rust code, and added "rustfmt" to the cspell.json dictionary.

Changes:

• Removed the separate "Searching for Code Patterns" section to reduce token count
• Condensed all guidance into a single, concise bullet point in the Code Generation section
• Removed redundant information while keeping the essential message:
  • Awareness that rustfmt formats method chains across multiple lines
  • Suggestion to use multi-line search patterns (rg with -U flag)
  • Alternative approach: search for individual method names
• Added "rustfmt" to .vscode/cspell.json word list in alphabetical order

This addresses the issue while being much more token-efficient.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Update Copilot instructions to search for call chains across multiple lines</issue_title>
<issue_description>I've noticed lately that Copilot often greps for function call chains like obj.foo().bar() when, in fact, rustfmt might've reformatted it across multiple lines like,

obj
    .foo()
    .bar();

Update the copilot-instructions.md to take this into account whenever it's grep'ing for function call chains.</issue_description>

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

Fixes #3137

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[heaths]

@copilot was a whole section necessary? Won't this blow up our token count? Seems you could provide a few bullet points in the Code Generation section above or even add a new "Other Considerations" section for miscellaneous stuff like this. Be concise.

[Copilot]

Condensed it into a single bullet point in the Code Generation section. Removed the entire "Searching for Code Patterns" section to reduce token count. (e25e19a → 8fd2f67)

[heaths]

Worth a try. I thought the individual instructions from before were better.

[heaths]

@copilot add "rustfmt" to .vscode/cspell.json's word list and make sure all checks pass.

[Copilot]

Pull Request Overview

This PR adds guidance to the Copilot instructions to help with searching multi-line function call chains in Rust code. The issue addressed is that Copilot was searching for method chains as single-line patterns when rustfmt typically formats them across multiple lines.

• Added a bullet point to remind about rustfmt's multi-line formatting of method chains
• Suggests using multi-line search patterns with rg -U flag or searching for individual method names
• Provides practical guidance to improve code search accuracy

[Copilot]

@copilot add "rustfmt" to .vscode/cspell.json's word list and make sure all checks pass.

Added "rustfmt" to .vscode/cspell.json word list in alphabetical order. JSON validation passed. (b97f8c0)