Update PlusModelCatalog URL

Author: Sunderlandkyl

features.md

@@ -61,7 +61,7 @@ Highlights
         Support of 8/16-bit grayscale, 24-bit RGB images in 2D+t and 3D+t image streams.  Ultrasound RF to B-mode conversion: brightness conversion and scan conversion, for linear and curvilinear transducers.
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       <td style="text-align: center;"><img src="{{ site.url }}/assets/images/ModelCatalog.png" /><br />
-        <a href="http://perk-software.cs.queensu.ca/plus/doc/nightly/modelcatalog/">Catalog of freely usable,<br />3D-printable models of tools and tracking fixtures</a>
+        <a href="https://pluslib.readthedocs.io/projects/PlusModelCatalog/en/latest/index.html">Catalog of freely usable,<br />3D-printable models of tools and tracking fixtures</a>
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       <td style="text-align: center;">&nbsp;</td>
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