Document inputs in the README

Signed-off-by: Douglas Camata <[email protected]>

README.md

@@ -9,12 +9,22 @@ This action installs Docker on a macOS runner through [Colima], [Lima-VM], and [
 I intend this action to be kept as simple as possible:
 
 - No other OS will be supported.
-- No other installation method for Colima will be supported (means you will always get what Homebrew gives you).
+- Binaries will be downloaded directly from the source when possible.
 
 ## Features
 
 - Safety check to ensure the action is running in macOS.
-- Caches big Homebrew packages to save some CI minutes.
+- As simple and lightweight (downloads binaries directly when possible).
+
+## Inputs
+
+## `inputs.upgrade-qemu` (defaults to `"false"`)
+
+The action, by default, will not try to upgrade QEMU if it's already installed.
+The reason is that installing QEMU takes a considerable amount of time.
+
+If this is set to `"true"`, the action will attempt an upgrade of QEMU to the
+latest version available in Homebrew.
 
 ## Outputs