ci: adds copilot instructions

.github/copilot-instructions.md

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+# Copilot Instructions
+
+## Commit Message Format
+
+Always use conventional commits format when creating commits. Follow this structure:
+
+```
+<type>(<scope>): <description>
+
+[optional body]
+
+[optional footer(s)]
+```
+
+### Types
+
+- **feat**: A new feature
+- **fix**: A bug fix
+- **docs**: Documentation only changes
+- **style**: Changes that do not affect the meaning of the code (white-space, formatting, etc)
+- **refactor**: A code change that neither fixes a bug nor adds a feature
+- **perf**: A code change that improves performance
+- **test**: Adding missing tests or correcting existing tests
+- **build**: Changes that affect the build system or external dependencies
+- **ci**: Changes to CI configuration files and scripts
+- **chore**: Other changes that don't modify src or test files
+
+### Scope
+
+The scope should indicate the package or area affected (e.g., `library`, `yaml-reader`, `hidi`).
+
+### Examples
+
+```
+feat(library): add support for pattern properties
+fix(yaml-reader): updates boolean serialization
+docs(README): update installation instructions
+ci(release): configure automated release workflow
+```
+
+### Breaking Changes
+
+If a commit introduces a breaking change, add `BREAKING CHANGE:` in the footer or append `!` after the type/scope:
+
+```
+feat(identity-emitter)!: change output format for models
+
+BREAKING CHANGE: The emitter now generates TypeScript interfaces instead of types
+```
+
+
+## Updating the benchmark information
+
+The user might request you update the benchmark information. You might do it on your own if a previous change added new properties to models under **src/Microsoft.OpenApi/Models**. Always use a separate commit for this change.
+
+To do so, run the following script:
+
+```shell
+cd performance/benchmark
+dotnet run -c Release
+```
+
+Then commit the report files using a "chore" commit.