Add the release notes for bitcoin-satellite v0.2.2

doc/release-notes/satellite/release-notes-0.2.2.md

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+Bitcoin Satellite 0.2.2 Release Notes
+====================
+
+Bitcoin Satellite version 0.2.2 is now available for Ubuntu, Fedora, and CentOS
+at:
+
+  - [Launchpad (Debian packages)](https://launchpad.net/~blockstream/+archive/ubuntu/satellite)
+  - [Copr (RPM package)](https://copr.fedorainfracloud.org/coprs/blockstream/satellite/)
+
+This minor release includes small improvements and bug fixes.
+
+Please report bugs using the issue tracker:
+
+  <https://github.com/Blockstream/bitcoinsatellite/issues>
+
+Alternatively, contact us at:
+
+  - <https://help.blockstream.com/>
+  - #blockstream-satellite IRC channel on freenode
+
+How to Upgrade
+==============
+
+The easiest way to upgrade is by using
+[`blocksat-cli`](https://blockstream.github.io/satellite/doc/quick-reference.html),
+the Blockstream Satellite command-line interface (CLI). Assuming you already
+have it installed, run:
+
+```
+blocksat-cli deps update --btc
+```
+
+Otherwise, you can [install the
+CLI](https://blockstream.github.io/satellite/doc/quick-reference.html#cli-installation-and-upgrade)
+and run the above command.
+
+Alternatively, you can upgrade Bitcoin Satellite manually by running the
+following commands:
+
+Ubuntu:
+```
+add-apt-repository ppa:blockstream/satellite
+apt-get update
+apt-get install --only-upgrade bitcoin-satellite
+```
+
+Fedora:
+```
+dnf copr enable blockstream/satellite
+dnf upgrade bitcoin-satellite
+```
+
+CentOS:
+```
+yum copr enable blockstream/satellite
+yum upgrade bitcoin-satellite
+```
+
+Compatibility
+==============
+
+Bitcoin Satellite 0.2.2 is supported and tested on the following Linux distributions:
+- The latest two Ubuntu LTS releases.
+- The latest two Fedora releases.
+- CentOS 8.
+
+Bitcoin Core Version
+==============
+
+Bitcoin Satellite is a fork of Bitcoin Core. This specific release (version
+0.2.2) is based on Bitcoin Core 0.21.1.
+
+Notable changes
+===============
+
+Misbehavior on full synchronization via UDP multicast
+-----------------------------------
+
+The full node synchronization via UDP multicast (e.g., through the Blockstream
+Satellite stream) would previously fail if executed after the initial download
+of block headers from internet peers. For example, if the node had hybrid
+connectivity (satellite and internet) or spent some time connected on the
+peer-to-peer (p2p) network before initiating the full sync via UDP multicast
+only. In both cases, the node would likely download all block headers over the
+internet. After that, any block received via UDP multicast would be ignored
+whenever the corresponding header was already downloaded, as if the entire block
+was already available.
+
+This version fixes the condition for skipping an FEC-encoded block received via
+a UDP multicast stream. In addition to confirming the local block index already
+has an entry for the block, it also ensures the corresponding block data is
+available. Only in that scenario, it skips the FEC object to avoid unnecessary
+computations. By doing so, the satellite-based full synchronization procedure
+can run correctly despite a previous download of block headers over the
+internet.
+
+0.2.2 Changelog
+=================
+
+### FEC
+- Fix the blocking of file descriptors used to store partial FEC objects on
+  memory-mapped files. Release the descriptors immediately after memory mapping.
+
+### UDP Multicast Rx
+- Fix the skipping of FEC-encoded blocks with pre-existing entries on the local
+  block index. Skip an FEC block only if the corresponding hash is present on the
+  local index and the block data is entirely available.
+- Review the partial block timeout rule. Time blocks out based on the last
+  useful FEC chunk reception instead of the partial block creation timestamp.
+  Also, do not time out partial blocks coming from trusted peers while the local
+  node is not in sync with the trusted peers.
+- Review the filename of partial blocks stored in disk to fix the
+  incompatibility with NTFS file systems.
+- Fix runtime error thrown upon the reception of an unsupported txn codec. Drop
+  the partial block instead of crashing the application.
+
+### UDP Multicast Tx
+- Include the number of window blocks in the result returned by the
+  gettxwindowinfo RPC.
+