Allow single-letter variable names in camelCase rule and update examples

[Orrison]

This pull request makes targeted improvements to the CamelCase variable name rule, clarifying documentation, adjusting the regex logic to be more permissive, and updating test fixtures to reflect the intended behavior. The main focus is ensuring that single-letter variable names are allowed, and the regex for variable name validation is updated accordingly.

Rule logic adjustment:

• Updated the regex pattern in CamelCaseVariableNameRule.php to make the trailing group optional, allowing single-letter variable names to pass the validation.

Documentation update:

• Added a comment in CamelCaseVariableName.md to explicitly state that single-letter variables (e.g., $i) are valid.

Test fixture update:

• Added a single-letter variable assignment in ExampleClass.php to demonstrate and test that such variables are allowed.

Resolves #69

[Copilot]

Pull Request Overview

This PR refines the CamelCase variable name rule to properly allow single-letter variable names like $i by making the regex pattern more permissive and updating documentation and test fixtures to reflect this intended behavior.

Key Changes

• Updated regex pattern to make trailing camelCase groups optional, allowing single-letter variables
• Added documentation clarifying that single-letter variables are valid
• Enhanced test fixture with single-letter variable example

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/Rules/CamelCaseVariableName/CamelCaseVariableNameRule.php	Modified regex pattern to make trailing groups optional for single-letter variable support
docs/CamelCaseVariableName.md	Added documentation example showing single-letter variables are valid
tests/Rules/CamelCaseVariableName/Fixture/ExampleClass.php	Added test case with single-letter variable assignment