For those seeking a "readme" reader, easy stuff!
notepad.exe has been part of Windows since the 1980's. It will read/write text files, html, xml, bat, js, and a host of other text files. If it's a file that doesn't have a .txt extension, you must click "all files" in the "file open" dialog. Then, all will be visible.
If the readme has an extension of .wri, or rtf, you could use wordpad.exe. Also bundled with Windows, for a long time. This lets the author imbed bold, italics, font changes, font sizes, and other effects. In fact, if you don't use OLE database and spreadsheet imbedding in your word processing files, it could be a very nice primary word processor.
I have never, in all my life (I'm 66), owned an Apple product. I can't help you with what Apple uses for this.
To invoke either, either double click its icon, invoke it from the "start" menu, or click "start", then type it in "search programs and files" and press enter.
I hope this helps those who feel keyboard challenged. We all were there, once.