docs: add v2020.1.3 release notes

Signed-off-by: David Bauer <mail@david-bauer.net>

docs/index.rst

@@ -74,6 +74,7 @@ Several Freifunk communities in Germany use Gluon as the foundation of their Fre
    :caption: Releases
    :maxdepth: 1
 
+   releases/v2020.1.3
    releases/v2020.1.2
    releases/v2020.1.1
    releases/v2020.1

docs/releases/v2020.1.3.rst

+Gluon v2020.1.3
+===============
+
+Bugfixes
+--------
+
+- Fixes a bug in musl which can lead to spurious crashes in fastd and other programs, which alternate between single-
+  and multi-threaded operation. (`#2029 <https://github.com/freifunk-gluon/gluon/issues/2029>`_)
+
+- Fixes a regression which led to around 2.5 MiB higher memory usage for ar71xx-tiny and ramips-rt305x targets.
+  While this decreases the memory usage, the image will become around 64KiB larger. (`#2032 <https://github.com/freifunk-gluon/gluon/issues/2032>`_)
+
+- Fixes a bug which can cause the TP-Link TL-MR3020 v1 to become stuck in failsafe mode.
+
+
+Other changes
+-------------
+
+- Linux kernel has been updated to 4.14.180
+
+
+Known issues
+------------
+
+- High chance of ending in a soft-bricked state for Ubiquiti EdgeRouter-X. Workaround is to
+  repeat initial installation using the serial console. (`#1937 <https://github.com/freifunk-gluon/gluon/issues/1937>`_)
+
+- Out of memory situations with high client count on ath9k.
+  (`#1768 <https://github.com/freifunk-gluon/gluon/issues/1768>`_)
+
+- The integration of the BATMAN_V routing algorithm is incomplete.
+
+   - | Mesh neighbors don't appear on the status page. (`#1726 <https://github.com/freifunk-gluon/gluon/issues/1726>`_)
+     | Many tools have the BATMAN_IV metric hardcoded, these need to be updated to account for the new throughput
+     | metric.
+
+   - | Throughput values are not correctly acquired for different interface types.
+     | (`#1728 <https://github.com/freifunk-gluon/gluon/issues/1728>`_)
+     | This affects virtual interface types like bridges and VXLAN.
+
+- Default TX power on many Ubiquiti devices is too high, correct offsets are unknown
+  (`#94 <https://github.com/freifunk-gluon/gluon/issues/94>`_)
+
+  Reducing the TX power in the Advanced Settings is recommended.
+
+- The MAC address of the WAN interface is modified even when Mesh-on-WAN is disabled
+  (`#496 <https://github.com/freifunk-gluon/gluon/issues/496>`_)
+
+  This may lead to issues in environments where a fixed MAC address is expected (like VMware when promiscuous mode is
+  disallowed).
+
+- Inconsistent respondd API (`#522 <https://github.com/freifunk-gluon/gluon/issues/522>`_)
+
+  The current API is inconsistent and will be replaced eventually. The old API will still be supported for a while.
+