docs: Use a shorter link for installing Pavex (#424)

Author: LukeMathWalker

docs/getting_started/index.md

@@ -8,13 +8,13 @@ Execute one of the following commands to install it:
 === "shell"
 
     ```bash
-    curl --proto '=https' --tlsv1.2 -LsSf https://pavex.dev/releases/download/latest/pavex_cli-installer.sh | sh
+    curl --proto '=https' --tlsv1.2 -LsSf https://pavex.dev/install.sh | sh
     ```
 
 === "powershell"
 
     ```powershell
-    powershell -c "irm https://pavex.dev/releases/download/latest/pavex_cli-installer.ps1 | iex"
+    powershell -c "irm https://pavex.dev/install.ps1 | iex"
     ```
 
 ## Setup
@@ -52,4 +52,4 @@ You'll be asked to provide an **activation key** by `pavex self setup`.
 You can find the activation key for the beta program in the `#activation` channel of Pavex's Discord server.
 You can join the waiting list for the beta program on [pavex.dev](https://pavex.dev).
 
-If you need to change your activation key, invoke `pavex self activate`.
+If you need to change your activation key, invoke `pavex self activate`.