Update changelog

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changelog.md

@@ -19,6 +19,7 @@
    * Fixed a rare issue on Windows that could result in wesnoth.exe sticking around waiting for console input after encountering an error despite not being launched with the `--wconsole` option.
    * Fixed precise log timestamps missing a space between the timestamp and the log severity label.
    * Improve the in-game help's topic about orbs, add crowns and ellipses.
+   * Removed documentation for network proxy-related command line options previously removed in version 1.13.1 along with libana.
 
 ## Version 1.15.6
  ### Add-ons client