Add Zonda (#331)

* Add Zonda page

* GitHub Action: Apply external link format

* Change title

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Co-authored-by: mjaehn <[email protected]>

Author: mjaehn

docs/tools/SUMMARY.md

@@ -7,4 +7,5 @@
 * [Scaling Analysis](scaling_analysis.md)
 * [Spack](spack.md)
 * [SPICE](spice.md)
-* [Zephyr](zephyr.md)
+* [Zephyr](zephyr.md)
+* [Zonda](zonda.md)

docs/tools/zonda.md

@@ -0,0 +1,7 @@
+# <img src="https://polybox.ethz.ch/index.php/s/c8uZqrzwk45wpBx/download?path=%2Fpng&files=zonda-high-resolution-logo-transparent.png" width="110" valign="middle" alt="zonda"/> ICON Grid & EXTPAR Web Interface
+
+[Zonda :material-open-in-new:](https://zonda.ethz.ch/){:target="_blank"} is a web interface that facilitates generating EXTPAR data on ICON triangular grids for reasearch and on-demand simulations.
+
+The tool has been developed as a joint project by C2SM, MeteoSwiss and DWD. Zonda has been released in May 2025 and is publicly available.
+
+For further information, please consider the official [Zonda Docs :material-open-in-new:](https://zonda.ethz.ch/docs){:target="_blank"}.