`lineEnd` token isn't documented in the readme

[jaydenseric]

The lineEnd token isn't documented in the readme.

This is can cause confusion because the others are documented. I'm not even sure what lineEnd is, but I have to update jsdoc-md to account for it.

[brettz9]

It was added fairly recently (in #132 ) to allow for any carriage return to be encoded. Prior to that carriage returns were being dropped, so the change added a token to preserve them when present.