spec: Explain the BuildRequires on firewalld-filesystem
spec: Explain the BuildRequires on firewalld-filesystem

It's not immediately obvious why it is needed.

Suggested-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>
Signed-off-by: Andrea Bolognani <3ada0bee826c753786fdbba72243dfba997094cf@redhat.com>
Reviewed-by: Neal Gompa <8135daa3762340227c0c67f1c47ad07a127bd3a3@gmail.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

jfehlig/libvirt,nertpinx/libvirt,nertpinx/libvirt,zippy2/libvirt,libvirt/libvirt,jardasgit/libvirt,nertpinx/libvirt,jfehlig/libvirt,olafhering/libvirt,crobinso/libvirt,jardasgit/libvirt,jardasgit/libvirt,crobinso/libvirt,olafhering/libvirt,olafhering/libvirt,jfehlig/libvirt,zippy2/libvirt,libvirt/libvirt,zippy2/libvirt,crobinso/libvirt,libvirt/libvirt,jardasgit/libvirt,crobinso/libvirt,zippy2/libvirt,olafhering/libvirt,nertpinx/libvirt,nertpinx/libvirt,libvirt/libvirt,jardasgit/libvirt,jfehlig/libvirt