• #294: Add Healthchecks monitoring hook "ping_body_limit" option to configure how many bytes of
  logs to send to the Healthchecks server.
• #402: Remove the error when "archive_name_format" is specified but a retention prefix isn't.
• #420: Warn when an unsupported variable is used in a hook command.
• #439: Change connection failures for monitoring hooks (Healthchecks, Cronitor, PagerDuty, and
  Cronhub) to be warnings instead of errors. This way, the monitoring system failing does not block
  backups.
• #460: Add Healthchecks monitoring hook "send_logs" option to enable/disable sending borgmatic
  logs to the Healthchecks server.
• #525: Add Healthchecks monitoring hook "states" option to only enable pinging for particular
  monitoring states (start, finish, fail).
• #528: Improve the error message when a configuration override contains an invalid value.
• #531: BREAKING: When deep merging common configuration, merge colliding list values by appending
  them. Previously, one list replaced the other.
• #532: When a configuration include is a relative path, load it from either the current working
  directory or from the directory containing the file doing the including. Previously, only the
  working directory was used.
• Add a randomized delay to the sample systemd timer to spread out the load on a server.
• Change the configuration format for borgmatic monitoring hooks (Healthchecks, Cronitor,
  PagerDuty, and Cronhub) to specify the ping URL / integration key as a named option. The intent
  is to support additional options (some in this release). This change is backwards-compatible.
• Add emojis to documentation table of contents to make it easier to find particular how-to and
  reference guides at a glance.