docs: Add v2021.1.1 release notes

Signed-off-by: David Bauer <mail@david-bauer.net>
(cherry picked from commit d7f9e17f)

docs/index.rst

@@ -78,6 +78,7 @@ Several Freifunk communities in Germany use Gluon as the foundation of their Fre
    :caption: Releases
    :maxdepth: 1
 
+   releases/v2021.1.1
    releases/v2021.1
    releases/v2020.2.3
    releases/v2020.2.2

docs/releases/v2021.1.1.rst

+Gluon 2021.1.1
+==============
+
+Important notes
+---------------
+
+Upgrades to v2021.1 and later releases are only supported from releases v2018.2 and later. This is due to migrations that have been removed to simplify maintenance.
+
+
+Added hardware support
+----------------------
+
+
+ath79-generic
+~~~~~~~~~~~~~
+
+* Joy-IT
+
+    - JT-OR750i
+
+
+ramips-mt76x8
+~~~~~~~~~~~~~
+
+* Xiaomi
+
+    - Mi Router 4A (100M Edition)
+
+
+Bugfixes
+--------
+
+- Missing bandwith limit settings resulted in a respondd crash for v2021.1.
+
+- The Tunneldigger VPN provider was not registered with the Gluon VPN backend, resulting in broken Tunneldigger configurations.
+
+- Disabling Radio interfaces in v2021.1 could lead to nullpointer dereferences in the respondd airtime module, as the survey returns no data in this case.
+
+
+Known issues
+------------
+
+* Upgrading EdgeRouter-X from versions before v2020.1.x may lead to a soft-bricked state due to bad blocks on the NAND flash which the NAND driver before this release does not handle well.
+  (`#1937 <https://github.com/freifunk-gluon/gluon/issues/1937>`_)
+
+* 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.
+
+* In configurations without VXLAN, 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).