feat: add ignore option (fix #31) (#37)

- Add functionality to ignore files based on provided
regular expressions
- Support writeIndex and writeIndexCli
- in index.js config must be specified as below

    // @create-index {"ignore":["/foo.js"]}

src/utilities/constants.js

@@ -0,0 +1,2 @@
+// eslint-disable-next-line
+export const CREATE_INDEX_PATTERN = /(?:^|[\n\r]+)\/\/ @create-index\s?({.*})?[\n\r]+/;