[Docs] Update packetbeat-options.asciidoc (#36968)

Fix packetbeat documentation to avoid '{beatname}' being shown instead of the
correct beat name.

packetbeat/docs/packetbeat-options.asciidoc

@@ -57,7 +57,7 @@ packetbeat.interfaces.buffer_size_mb: 100
 [float]
 === Windows Npcap installation options
 
-On Windows {beatname} requires an Npcap DLL installation. This is provided by {beatname}
+On Windows {beatname_uc} requires an Npcap DLL installation. This is provided by {beatname_uc}
 for users of the Elastic Licenced version. In some cases users may wish to use
 their own installed version. In order to do this the `packetbeat.npcap.never_install`
 option can be used. Setting this option to `true` will not attempt to install the