Docs: update readme to indicate test-case-shorthand-strings is fixable

Author: not-an-aardvark

README.md

@@ -52,7 +52,7 @@ Name | ✔️ | 🛠 | Description
 [report-message-format](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/report-message-format.md) | | | Enforces a consistent format for report messages
 [require-meta-fixable](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/require-meta-fixable.md) | ✔️ | | Requires a `meta.fixable` property for fixable rules
 [no-missing-placeholders](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-missing-placeholders.md) | ✔️ | | Disallows missing placeholders in rule report messages
-[test-case-shorthand-strings](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/test-case-shorthand-strings.md) | | | Enforces consistent usage of shorthand strings for test cases with no options
+[test-case-shorthand-strings](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/test-case-shorthand-strings.md) | | 🛠 | Enforces consistent usage of shorthand strings for test cases with no options
 [prefer-placeholders](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/prefer-placeholders.md) | | | Disallows template literals as report messages
 [no-useless-token-range](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/no-useless-token-range.md) | ✔️ | 🛠 | Disallows unnecessary calls to sourceCode.getFirstToken and sourceCode.getLastToken
 [consistent-output](https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/master/docs/rules/consistent-output.md) | | | Enforces consistent use of output assertions in rule tests