fix(docs-infra): remove unwanted underline when hovering over contributor info links (#40944)

This commit removes an unwanted underline effect when hovering over
contributor info links (`.contributor-info > .info-item`). This was
accidentally introduced in #40427.

Before: ![contributor info on hover before][1]
After: ![contributor info on hover after][2]

[1]: https://user-images.githubusercontent.com/8604205/108560170-045a7580-7305-11eb-98d2-4302d98581c6.png
[2]: https://user-images.githubusercontent.com/8604205/108560176-058ba280-7305-11eb-97eb-74cf2c830a39.png

PR Close #40944

aio/src/styles/2-modules/_contributor.scss

@@ -65,6 +65,7 @@ aio-contributor {
 
       &:hover {
         color: $lightgray;
+        text-decoration: none;
       }
 
       &.icon {