Update changelog

docs/changelog.md

@@ -47,6 +47,8 @@ SPDX-FileCopyrightText: 2011-2021 Carles Fernandez-Prades <carles.fernandez@cttc
 - Provide hints to the user in case of failed flow graph connection due to
   inconsistencies in the configuration file.
 - Fix segmentation fault if the RINEX output was disabled.
+- Added a feature that optionally enables the remote monitoring of GPS and
+  Galileo ephemeris using UDP and protobuffers.
 
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