docs: make README banner full-width and add changeset (#13)

Co-authored-by: jpoehnelt-bot <jpoehnelt-bot@users.noreply.github.com>

.changeset/readme-banner-full-width.md

@@ -0,0 +1,5 @@
+---
+"@googleworkspace/cli": patch
+---
+
+Improve README branding by making the hero banner full-width.

README.md

@@ -1,5 +1,5 @@
 <p align="center">
-  <img src="https://raw.githubusercontent.com/googleworkspace/cli/refs/heads/main/docs/logo.png" alt="gws logo" width="200">
+  <img src="https://raw.githubusercontent.com/googleworkspace/cli/refs/heads/main/docs/logo.jpg" alt="gws logo" width="100%">
 </p>
 
 <h1 align="center">gws</h1>