message: rage: Add installation method for openSUSE Tumbleweed
  Closes str4d/rage#210.
diff: @@ -131,6 +131,7 @@ encrypted to a specific public key.
  |-------------|-------------|
  | Cargo (Rust 1.51+) | `cargo install rage` |
  | Homebrew (macOS or Linux) | `brew tap str4d.xyz/rage https://str4d.xyz/rage`<br>`brew install rage` |
  +| openSUSE Tumbleweed | `zypper install rage-encryption` |
  On Windows, Linux, and macOS, you can use the
  [pre-built binaries](https://github.com/str4d/rage/releases).
  