doc: Add Tracing with Tracy

doc/tracing-tracy.md

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+# Tracing with Tracy {#tracing-tracy}
+
+<!--
+Copyright 2022, Collabora, Ltd. and the Monado contributors
+SPDX-License-Identifier: BSL-1.0
+-->
+
+## Requirements
+
+One of the tracing backends Monado has is [Tracy][]. Note, that the backend is
+fully integrated so you only need to make sure that the correct CMake flags are
+set, `XRT_HAVE_TRACY` and `XRT_FEATURE_TRACING`. Building the [Tracy][] profiler
+is also required, but the order doesn't matter.
+
+* Get the [Tracy][] profiler.
+  * **Linux**: build it, needs `glfw3`, `freetype2` & `capstone` dev packages.
+  * **Windows**: download release binaries from page, or build it.
+* Build Monado with `XRT_FEATURE_TRACING` & `XRT_HAVE_TRACY` being `ON`.
+
+## Running
+
+Start the [Tracy][] profiler, either try to connect directly to the host you
+want to run Monado on, or wait for it to show up in the first initial UI. Then
+run Monado like you normally would, for example like below.
+
+```bash
+monado-serivce
+```
+
+## Notes
+
+Unlike @ref tracing-perfetto Tracy supports Windows, it also supports live
+viewing of the data stream. But Tracy can only trace on application at a time
+where as Perfetto can do multiple processes at the same time and whole system
+tracing giving a higher level overview of the whole system.
+
+[Tracy]: https://github.com/wolfpld/tracy