chore(doc): add padding in version selector elements on the documentation (#6698)

## 📄 Description

For better readability, there is a padding added around
version-selectors on v10.

## 🚀 Demo

Padding added for top and bottom (8px), and right and left (12px) to
keep it consistent to v9 of the Design System Webpage.

<img width="1907" height="603" alt="image"
src="https://github.com/user-attachments/assets/274ca6c5-2ecd-4d48-a169-d491a24a655a"
/>

---

## 🔮 Design review

- [ ] Design review done
- [x] No design review needed

---------

Co-authored-by: Nattaya Buck <[email protected]>
Co-authored-by: Lea <[email protected]>

Author: 3 people

.changeset/some-parts-raise.md

@@ -0,0 +1,5 @@
+---
+'@swisspost/design-system-documentation': patch
+---
+
+Added padding in the version selector for better readability.

packages/documentation/.storybook/addons/addons.scss

@@ -1,8 +1,4 @@
 @use '@swisspost/design-system-styles/core' as post;
-@use '@swisspost/design-system-styles/functions/tokens' as tokens;
-@use '@swisspost/design-system-styles/tokens/utilities' as utilities;
-
-tokens.$default-map: utilities.$post-spacing;
 
 .addon-label {
   color: var(--post-current-fg) !important;
@@ -12,19 +8,19 @@ tokens.$default-map: utilities.$post-spacing;
   min-width: 12rem;
   display: flex;
   flex-flow: column nowrap;
-  gap: tokens.get('utility-gap-2');
+  gap: 0.125rem;
   position: absolute;
   top: -5px;
   right: 0;
-  padding: tokens.get('utility-gap-8');
+  padding: 0.5rem;
   background-color: post.$white;
   border: post.$border-width solid post.$border-color;
   border-radius: post.$border-radius;
   font-size: 0.875rem;
 
   .addon-dropdown__item {
     display: block;
-    padding: tokens.get('utility-gap-8') tokens.get('utility-gap-12');
+    padding: 0.5rem 0.75rem;
     border-radius: post.$border-radius-sm;
     text-decoration: none;
     color: var(--post-current-fg) !important;
@@ -42,6 +38,6 @@ tokens.$default-map: utilities.$post-spacing;
 .addon-button {
   post-icon {
     font-size: 1.25rem;
-    margin-inline-end: tokens.get('utility-gap-2');
+    margin-inline-end: 0.125rem;
   }
 }