Update base in tokens docs (#2547)

## Summary:
The base for calculating pixel equivalents was still listed as `8`, so the token docs were outdated. This PR updates that hard-coded value to `10`! 

Issue: WB-1914

## Test plan:
1. Visit the token docs page /?path=/docs/packages-tokens-sizing--docs
2. Look at the values in the "Pixels (equivalent)" column
3. The values should be base 10, such as sizing.size_180 / 1.8x / 1.8rem / 18

Author: marcysutton

Reviewers: beaesguerra

Required Reviewers:

Approved By: beaesguerra

Checks: ✅ 12 checks were successful, ⏭️  2 checks have been skipped

Pull Request URL: #2547

Author: marcysutton

.changeset/dry-eagles-relate.md

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

__docs__/wonder-blocks-tokens/tokens-sizing.mdx

@@ -51,7 +51,7 @@ const styles = {padding: sizing.size_160};
         },
         {
             label: "Pixels (equivalent)",
-            cell: (row) => parseFloat(row.value.replace("rem", "") * 8),
+            cell: (row) => parseFloat(row.value.replace("rem", "") * 10),
         },
         {
             label: "Example",