fix: files/ignores behavior is wrong in doc

[HerringtonDarkholme]

wrong doc:

• files takes precedence

correct behavior:

• ignores will be tested if present, ast-grep will skip file if it matches
• otherwise, files will be test against files, if the option present. the file will be included if and only if it matches one of the glob in the files list.
• if neither ignores/files is configured, a file is included by default