Use .prettierrc.json instead of eslint prettier rule to configure format options

[marcalexiei]

During #648 I have some clash between Prettier and ESLint:
I'm using an editor with support for both tools, however they have a different behaviour when dealing with quotes:

• eslint was using single quotes due to the inline configuration of eslint.config.js
  

  eslint-doc-generator/eslint.config.js

  Lines 28 to 33 in f733170

  	'prettier/prettier': [
  	'error',
  	{
  	singleQuote: true,
  	},
  	],

• prettier was using the double quotes, which is prettier default due to the empty config in .prettierrc.json
  

  eslint-doc-generator/.prettierrc.json

  Line 1 in f733170

  {}

To resolve this inconsistency, I added the singleQuote option to .prettierrc.json and removed it from eslint.config.js.
There should be no further issues since the ESLint plugin now reads options directly from Prettier's configuration:
https://github.com/prettier/eslint-plugin-prettier?tab=readme-ov-file#options

[bmish]

Thanks!