docs: Update links in README

[regseb]

Update links in README to fix CI Check links.

• https://cheerio.js.org/docs/basics/selecting → https://cheerio.js.org/docs/basics/selecting/ : Follow the redirect that adds a slash at the end.
• https://github.com/NaturalIntelligence/fast-xml-parser/blob/HEAD/docs/v4/4.XMLValidator.md → https://github.com/NaturalIntelligence/fast-xml-parser/blob/HEAD/docs/v4%2C%20v5/4.XMLValidator.md : The v4 directory has been renamed to v4, v5.
• https://cheerio.js.org/docs/api/classes/Cheerio → https://cheerio.js.org/docs/api/classes/cheerio/ : The class name is written in lowercase.