Wrong link in 4.5.1 release description

[djibe]

Hi,
in your awesome 4.5.1 doc release, it looks like there is a small glitch.

Docs
#30957: Add .card-img-bottom example

But this reference is linking to #30957: Nullify custom form states' box-shadow

Thanks.

[XhmikosR]

/CC @mdo

I guess we'd need to update the blog post too

[mdo]

Removed the change in both spots for now.