message: Update binaries information to mention snap
diff: @@ -19,8 +19,11 @@ class reference.
  Installing
  ============
  -Binary easily-installable packages are provided for Windows and macOS and are
  -part of many Linux distributions.
  +Easily-installable prebuilt binaries are provided for Windows and macOS and
  +available from https://poedit.net/download.
  +
  +Official binaries for Linux are available as a Snap at https://snapcraft.io/poedit
  +Most Linux distributions also include native Poedit packages.
  Installing from sources
  