Ignore image alt text in title

[koppor]

We use images in the headings to be more welcoming to newcomers:

## Choosing a task [![Join the chat at https://gitter.im/JabRef/jabref](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/JabRef/jabref)

I would expect the image alt text not to be presnt

- [Choosing a task](#choosing-a-task-join-the-chat-at-httpsgitterimjabrefjabref)

But it is included

- [Choosing a task Join the chat at https://gitter.im/JabRef/jabref]...