message: doc(CLI-INSTALLATION): Make headings h3
diff: -macOS and GNU/Linux
  --------------------
  +### macOS and GNU/Linux
  - Extract the `.tar.gz` package by running:
  @@ -16,8 +15,7 @@ tar fvx path/to/cli.tar.gz
  export PATH="$PATH:/opt/etcher-cli"
  ```
  -Windows
  --------
  +### Windows
  - Unzip the `.zip` package by right-clicking on it and selecting "Extract All"
  @@ -45,15 +43,13 @@ Windows
  - Re-open `cmd.exe`, or PowerShell
  -Running
  --------
  +### Running
  ```sh
  etcher -v
  ```
  -Options
  --------
  +### Options
  ```
  --help, -h show help
  @@ -63,5 +59,3 @@ Options
  --yes, -y confirm non-interactively
  --unmount, -u unmount on success
  ```
  -
  -
  