DEVDOCS-6087: [update] add favicon to storefront GraphQL (#484)

<!-- Ticket number or summary of work -->
# [DEVDOCS-6087]


## What changed?
Added example mutation to get a storefront's favicon.


## Release notes draft

* The example query shows you how to get a storefront's favicon.
 

## Anything else?
<!-- Add related PRs, salient notes, additional ticket numbers, etc. -->

ping {names}


[DEVDOCS-6087]:
https://bigcommercecloud.atlassian.net/browse/DEVDOCS-6087?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

---------

Co-authored-by: Nathan Booker <[email protected]>

docs/storefront/graphql/examples/index.mdx

@@ -65,7 +65,7 @@ query CustomerAttributes {
 }
 ```
 
-<a href="https://developer.bigcommerce.com/graphql?playground_tab=customerDetails" target="_blank">**Try it in GraphQL Playground**</a>
+<a href="https://developer.bigcommerce.com/graphql-storefront/playground" target="_blank">**Try it in GraphQL Playground**</a>
 
 ## Get first three levels of category tree
 
@@ -91,7 +91,7 @@ fragment CategoryFields on CategoryTreeItem {
 }
 ```
 
-<a href="https://developer.bigcommerce.com/graphql?playground_tab=categoryTree" target="_blank">**Try it in GraphQL Playground**</a>
+<a href="https://developer.bigcommerce.com/graphql-storefront/playground" target="_blank">**Try it in GraphQL Playground**</a>
 
 ## Get category and products within by URL
 
@@ -146,7 +146,7 @@ fragment PriceFields on Money {
 }
 ```
 
-<a href="https://developer.bigcommerce.com/graphql?playground_tab=categoriesByUrl" target="_blank">**Try it in GraphQL Playground**</a>
+<a href="https://developer.bigcommerce.com/graphql-storefront/playground" target="_blank">**Try it in GraphQL Playground**</a>
 
 ## Look up an object by URL
 
@@ -187,7 +187,7 @@ query LookUpUrl {
 }
 ```
 
-<a href="https://developer.bigcommerce.com/graphql?playground_tab=objectsByUrl" target="_blank">**Try it in GraphQL Playground**</a>
+<a href="https://developer.bigcommerce.com/graphql-storefront/playground" target="_blank">**Try it in GraphQL Playground**</a>
 
 ## Get popular brands
 
@@ -208,4 +208,18 @@ query {
 }
 ```
 
-<a href="https://developer.bigcommerce.com/graphql?playground_tab=popularBrands" target="_blank">**Try it in GraphQL Playground**</a>
+<a href="https://developer.bigcommerce.com/graphql-storefront/playground" target="_blank">**Try it in GraphQL Playground**</a>
+
+## Get a favicon to Storefront GraphQL
+
+```graphql filename="Example query: Get the storefront's favicon" showLineNumbers copy
+query Favicon {
+  site {
+    settings {
+      faviconUrl
+    }
+  }
+}
+```
+
+<a href="https://developer.bigcommerce.com/graphql-storefront/playground" target="_blank">**Try it in GraphQL Playground**</a>