message: docs: add note about individual autocompletion files
diff: @@ -310,6 +310,8 @@ The release binaries are packaged with shell auto-completion files for bash, fis
  - For PowerShell, add `. _btm.ps1` to your PowerShell
  [profile](<https://docs.microsoft.com/en-us/previous-versions//bb613488(v=vs.85)>).
  +The individual auto-completion files are also included in the stable/nightly releases as `completion.tar.gz`.
  +
  ## Usage
  You can run bottom using `btm`.
  