Remove user bio feature (#1214)

The feature is very limited in scope, and we hope for community
extensions to take over this feature and make it much better.

less/forum/UserCard.less

@@ -90,37 +90,6 @@
     display: inline-block;
     margin-right: 15px;
   }
-  .item-bio {
-    display: block;
-    margin: 0;
-  }
-}
-.UserBio {
-  margin: -10px -10px 10px;
-  border: 1px dashed transparent;
-  border-radius: @border-radius;
-
-  &.editable:not(.editing) {
-    cursor: text;
-
-    &:hover {
-      border-color: rgba(255, 255, 255, 0.2);
-    }
-  }
-  &, textarea {
-    font-size: 14px;
-  }
-  textarea {
-    padding: 10px;
-    font-size: 14px;
-    resize: none;
-  }
-}
-.UserBio-content {
-  padding: 10px 10px 1px;
-}
-.UserBio-placeholder {
-  opacity: 0.3;
 }
 .UserCard-lastSeen {
   & .icon {