Use double-colons before pseudo-elements

The css/examples.icons.css file contains the following lines.

.toolbar-bar .toolbar-icon-examples:before,
.toolbar-bar .toolbar-icon-examples:active:before,
.toolbar-bar .toolbar-icon-examples.active:before {
  background-image: url(../images/examples.svg);
}

Before a pseudo-element there should be two colons. The correct lines are the following ones.

.toolbar-bar .toolbar-icon-examples::before,
.toolbar-bar .toolbar-icon-examples:active::before,
.toolbar-bar .toolbar-icon-examples.active::before {
  background-image: url(../images/examples.svg);
}

As a side note, the description given for @file needs to be changed to Styling for the Examples module icons.