fix(docs): table bottom border color missing (#49955)

## What kind of change does this PR introduce?

bug fix on table ui in docs

## What is the current behavior?

currently a recent change in
[#47288](https://github.com/supabase/supabase/pull/47288/changes#diff-57e15cf799459c10344c86d8ec797a16f0d3e824386e85552cb653594f7e616aR118)
made table bottom border color dimmed down vs others.

## What is the new behavior?

- fixes bottom border by targeting only border within the table (if that
was the initial intent?)

| state | preview |
| -------|------|
| before | <img width="787" height="320" alt="image"
src="https://github.com/user-attachments/assets/70eac743-255d-4848-9488-752e91a8793e"
/> |
| after | <img width="787" height="320" alt="image"
src="https://github.com/user-attachments/assets/e307dc33-6247-4f36-89d0-75d1eb1aef4e"
/> |

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Style**
* Refined table styling so bottom borders appear only between body rows,
removing the border from the final row.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/config/typography.config.js

@@ -114,7 +114,7 @@ module.exports = {
               border: '1px solid var(--border-default)',
               borderRadius: 'var(--radius-lg)',
             },
-            td: {
+            'tbody tr:not(:last-child) td': {
               borderBottom: '1px solid var(--background-surface-200)',
             },
             code: {