update readme

Author: SimonBlanke

README.md

@@ -19,18 +19,9 @@ Test functions for benchmarking optimization algorithms in Python.
   <a href="https://codecov.io/gh/SimonBlanke/Surfaces"><img src="https://img.shields.io/codecov/c/github/SimonBlanke/Surfaces?style=flat-square" alt="Coverage"></a>
 </p>
 
-<table align="center">
-  <tr>
-    <th align="right">Documentation</th>
-    <th align="center">▸</th>
-    <th align="left"><a href="https://github.com/SimonBlanke/Surfaces">Homepage</a> · <a href="https://github.com/SimonBlanke/Surfaces#usage">User Guide</a> · <a href="https://github.com/SimonBlanke/Surfaces#function-categories">API Reference</a> · <a href="https://github.com/SimonBlanke/Surfaces#examples">Tutorials</a></th>
-  </tr>
-  <tr>
-    <td align="right"><b>On this page</b></td>
-    <td align="center">▸</td>
-    <td align="left"><a href="#key-features">Features</a> · <a href="#examples">Examples</a> · <a href="#core-concepts">Concepts</a> · <a href="#citation">Citation</a></td>
-  </tr>
-</table>
+| **Documentation** | ▸ | [Homepage](https://github.com/SimonBlanke/Surfaces) · [User Guide](https://github.com/SimonBlanke/Surfaces#usage) · [API Reference](https://github.com/SimonBlanke/Surfaces#function-categories) · [Tutorials](https://github.com/SimonBlanke/Surfaces#examples) |
+| ---: | :---: | :--- |
+| **On this page** | ▸ | [Features](#key-features) · [Examples](#examples) · [Concepts](#core-concepts) · [Citation](#citation) |
 
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