This is an old revision of the document!
Disable double-shift in Intellij IDEA
https://youtrack.jetbrains.com/issue/IDEA-114933#comment=27-603899
Open lib/resources.jar/idea/PlatformActions.xml and remove or comment such line:
<action id="SearchEverywhere" class="com.intellij.ide.actions.SearchEverywhereAction" />