adding cover alt text

The picture above has nothing to do with the post, except that I just finished updating <meta>
tags in the templates and now posts with pictures can have link preview with pictures, while having custom alt
text in the post.
If you are using the same hugo terminal theme
like this blog, you can do it by overriding the partials (by default, the alt text is post title, which I think isn’t quite enough for the way I post pictures).