Embedded reference doesn't work when the section has parenthesis

[aadimator]

First of all, thanks for such an amazing tool. This has been really helpful for me.

One problem I encountered is that when an embedded reference section has parenthesis in the heading, it is unable to find that.

In this image, we can see that the tool works perfectly fine for the above embed, but the second one results in a full-page embed.

After a lot of debugging (A LOT, especially as I have never coded in Rust) , println!("{} : {}", section.to_lowercase(), cowstr.to_string().to_lowercase()); results in the follwoing output.

We can see that section ignores the parenthesis, while cowstr doesn't.

For now, I have resorted to removing the parenthesis from the reference heading. I just wanted to bring this to your attention.

Thanks and regards.