docs: Update setup instructions on landing page (#184)

docs/README.md

@@ -25,20 +25,30 @@ footer: ISC Licensed | Copyright © 2019-present Starship Contributors
 
 1. Install the **starship** binary:
 
-    ```bash
-    cargo install starship
+   **[Download archives of precompiled binaries](https://github.com/starship/starship/releases)** if you don't use the platforms below.
+
+   #### Homebrew
+
+   ```sh
+   $ brew install starship
+   ```
+
+   #### Rust (v1.33 or higher)
+
+   ```sh
+   $ cargo install starship
    ```
 
 1. Add the init script to your shell's config file:
 
-    #### Bash / Zsh
+   #### Bash
 
-    Add the following to the end of `~/.bashrc` or `~/.zshrc`:
+   Add the following to the end of `~/.bashrc`:
 
-    ```bash
-    # ~/.bashrc or ~/.zshrc
+   ```sh
+   # ~/.bashrc
 
-    eval "$(starship init $0)"
+   eval "$(starship init bash)"
    ```
 
    #### Fish
@@ -50,3 +60,13 @@ footer: ISC Licensed | Copyright © 2019-present Starship Contributors
 
    eval (starship init fish)
    ```
+
+   #### Zsh
+
+   Add the following to the end of `~/.zshrc`:
+
+   ```sh
+   # ~/.zshrc
+
+   eval "$(starship init zsh)"
+   ```