WiFi driver is stable now.

Flash instructions in the OpenWRT Commit: https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=eae6cac6a30b95bef04d033ed8a303b7e35a078b

We only support v1, not v2 or v3.

At the December 2019 review day, the behavior for LAN only devices was
defined. Such devices will use each LAN port as WAN.

Hardware specification:
- SOC: Qualcomm QCA9563 @ 775MHz
- Flash: GigaDevice GD25Q64CSIG (8MiB)
- RAM: Zentel A3R1GE40JBF (128 MiB DDR2)
- Ethernet: Qualcomm QCA8337N: 4x 1Gbps LAN + 1x 1Gbps WAN
- Wireless:
  - 2.4GHz (bgn) QCA9563 integrated (3x3)
  - 5GHz (ac) Qualcomm QCA9886 (2x2)
- Button: 1x power, 1x reset, 1x wps
- LED: 6x LEDs: power, wlan2g, wlan5g, lan, wan, wps
- UART: There's no UART header on the board

This commit removes the broken flag for the ipq806x-generic target,
as the first device (NETGEAR R7800) now has full support in Gluon

This commit accounts for the target renaming which was done in upstream
commit 7407e723991 ("ipqx0xx: add Generic subtarget")

Their kernel partition is too small, the OpenWrt build system
is unable to create an image.

The kernel partition on these devices is too small for the
OpenWrt 19.07 kernel. It is also located after the rootfs, so
we cannot grow it further.

Therefore mark these devices as deprecated now.

This adds documentation for the gluon-mesh-batman-adv package and
elaborates on its build and configuration options, as well as
the implemented multicast architecture.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>

Issue was uncovered by sphinx-build:
docs/user/getting_started.rst:100: WARNING: Definition list ends without a blank line; unexpected unindent.