ADD: added Catch2 test; added TrackClass

libs/Catch2/docs/commercial-users.md

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+<a id="top"></a>
+# Commercial users of Catch
+
+As well as [Open Source](opensource-users.md#top) users Catch is widely used within proprietary code bases too.
+Many organisations like to keep this information internal, and that's fine, 
+but if you're more open it would be great if we could list the names of as
+many organisations as possible that use Catch somewhere in their codebase. 
+Enterprise environments often tend to be far more conservative in their tool adoption - 
+and being aware that other companies are using Catch can ease the path in.
+
+So if you are aware of Catch usage in your organisation, and are fairly confident there is no issue with sharing this
+fact then please let us know - either directly, via a PR or 
+[issue](https://github.com/philsquared/Catch/issues), or on the [forums](https://groups.google.com/forum/?fromgroups#!forum/catch-forum).
+ 
+ - Bloomberg
+ - [Bloomlife](https://bloomlife.com)
+ - NASA
+ - [Inscopix Inc.](https://www.inscopix.com/)
+ - [Makimo](https://makimo.pl/)
+ - [UX3D](https://ux3d.io)
+ - [King](https://king.com)
+