Uplifted Content Design Pages (#13012)

### WHY are these changes introduced?

Updated content design pages based on uplift work to bring our published
standards in line with current standards. These are updates to
documentation only for polaris.shopify.com.

### WHAT is this pull request doing?

- New Fundamentals page to replace the Product content page
- Remove pages no longer needed (Actionable language, Help content, Help
documentation, Merchant-to-customer content, and Voice and tone)
- Updated Grammar page
- Updated Error messages page
- Updated page order for side nav
- Moved button  content guidelines to button compontent page
- Added redirects for removed pages

<img width="1370" alt="Shopify Polaris Content Guidelines"
src="https://github.com/user-attachments/assets/e3bc526a-d56c-4376-b343-058326d2a1fc"
/>

### How to 🎩

🖥 [Local development
instructions](https://github.com/Shopify/polaris/blob/main/README.md#install-dependencies-and-build-workspaces)
🗒 [General tophatting
guidelines](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md)
📄 [Changelog
guidelines](https://github.com/Shopify/polaris/blob/main/.github/CONTRIBUTING.md#changelog)

### 🎩 checklist

- [ ] Tested a
[snapshot](https://github.com/Shopify/polaris/blob/main/documentation/Releasing.md#-snapshot-releases)
- [ ] Tested on
[mobile](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md#cross-browser-testing)
- [x] Tested on [multiple
browsers](https://help.shopify.com/en/manual/shopify-admin/supported-browsers)
- [ ] Tested for
[accessibility](https://github.com/Shopify/polaris/blob/main/documentation/Accessibility%20testing.md)
- [x] Updated the component's `README.md` with documentation changes
- [x] [Tophatted
documentation](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting%20documentation.md)
changes in the style guide

.changeset/orange-spoons-fix.md

@@ -0,0 +1,2 @@
+---
+---

polaris.shopify.com/content/components/actions/button-group.mdx

@@ -58,7 +58,7 @@ Button groups should:
 
 ## Content guidelines
 
-Button groups should follow the [content guidelines](https://polaris.shopify.com/content/actionable-language#buttons) for buttons.
+Button groups should follow the [content guidelines](https://polaris.shopify.com/components/actions/button#content-guidelines) for buttons.
 
 ---
 

polaris.shopify.com/content/components/actions/button.mdx

@@ -117,7 +117,60 @@ The HTML that renders for the `Button` and `Link` components carries meaning. Us
 
 ## Content guidelines
 
-Buttons should follow the content guidelines for [buttons](https://polaris.shopify.com/content/actionable-language#buttons).
+{/* keywords: buttons, button copy, button text, button content, links, actions, calls to action, call to actions, action-led, action led, scannable, articles, choose , select, choose vs select, select vs choose, need, must, need vs must, must vs need --> --> */}
+
+Buttons need to be clear and predictable. Merchants should be able to anticipate what will happen when they select a button. Never mislead someone by mislabeling a button.
+
+- Use universally understood iconography instead of words wherever you can
+- Buttons can include an icon or text, or both
+- Verbs like “View” or “Go” or “Read” are often unnecessary since the button itself already conveys these actions
+- Sentence case
+- No articles (“a” “an” “the”)
+- No punctuation
+
+<DoDont>
+
+#### Do
+
+- Save
+- Edit
+- Add tags
+
+#### Don’t
+
+- Save product
+- Edit collection
+- Add tag(s)
+
+</DoDont>
+
+Always write button text in sentence case, which means the first word is capitalized and the rest are lowercase (unless a term is a proper noun).
+
+<DoDont>
+
+#### Do
+
+- Buy new domain
+
+#### Don’t
+
+- Buy New Domain
+
+</DoDont>
+
+Avoid unnecessary words and articles such as “the,” “an,” or “a.”
+
+<DoDont>
+
+#### Do
+
+Add menu item
+
+#### Don’t
+
+Add a menu item
+
+</DoDont>
 
 ---