missing manpage for bridge.conf

There's currently no (easy) way to figure out the form of content of `/etc/qemu/bridge.conf`. Some howtos (e.g. https://wiki.archlinux.org/index.php/QEMU#Bridged_networking_using_qemu-bridge-helper) mention `bridge.conf.sample` which is not available according to `apt-file` and the official wiki at wiki.qemu.org doesn't mention the file at all, it seems necessary, though, because specification of `-net nic -net bridge,br=bridge0` fails with `failed to get mtu of bridge `bridge0': No such device` (can't be investigated further because setup is completely unclear).

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: qemu 2.1+dfsg-4ubuntu6.4
Uname: Linux 3.19.0-031900-generic x86_64
ApportVersion: 2.14.7-0ubuntu8.2
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Feb 21 19:39:07 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2015-01-26 (25 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
KvmCmdLine:
 COMMAND         STAT  EUID  RUID   PID  PPID %CPU COMMAND
 kvm-irqfd-clean S<       0     0  1026     2  0.0 [kvm-irqfd-clean]
 qemu-system-x86 Sl+      0     0 25905 25904 11.9 qemu-system-x86_64 -boot c -hda ubuntu.img -m 2048 -smp 16 -enable-kvm -vnc :0,abc -k de -drive file=/dev/sda14,if=ide -net nic -net bridge,br=bridge0
 kvm-pit/25905   S        0     0 25948     2  0.0 [kvm-pit/25905]
MachineType: LENOVO 20221
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.19.0-031900-generic root=UUID=ac20c93a-0ec5-445a-98cd-941f0fbc0e50 ro rootflags=subvol=@
SourcePackage: qemu
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/12/2013
dmi.bios.vendor: LENOVO
dmi.bios.version: 71CN51WW(V1.21)
dmi.board.asset.tag: No Asset Tag
dmi.board.name: INVALID
dmi.board.vendor: LENOVO
dmi.board.version: 31900003WIN8 STD MLT
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Lenovo IdeaPad Z500 Touch
dmi.modalias: dmi:bvnLENOVO:bvr71CN51WW(V1.21):bd07/12/2013:svnLENOVO:pn20221:pvrLenovoIdeaPadZ500Touch:rvnLENOVO:rnINVALID:rvr31900003WIN8STDMLT:cvnLENOVO:ct10:cvrLenovoIdeaPadZ500Touch:
dmi.product.name: 20221
dmi.product.version: Lenovo IdeaPad Z500 Touch
dmi.sys.vendor: LENOVO




This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/113