avoid using `this.set` (fixes #1275) (#1276)
avoid using `this.set` (fixes #1275) (#1276)

Right now, the DocsKeyboardShortcutsComponent attempts to use `this.set`
to set a property. DocsKeyboardShortcutsComponent is a Glimmer
Component, so this API is not available.  To avoid the problem, let's
use a regular assignment statement.
ember-learn/ember-cli-addon-docs,ember-learn/ember-cli-addon-docs,ember-learn/ember-cli-addon-docs