doc: tell that unit-tests "priority" is introduced in 0.52 [skip ci]
@@ -54,6 +54,8 @@ $ MESON_TESTTHREADS=5 ninja test
Priorities
--
+*(added in version 0.52.0)*
+
Tests can be assigned a priority that determines when a test is *started*. Tests with higher priority are started first, tests with lower priority started later. The default priority is 0, meson makes no guarantee on the ordering of tests with identical priority.
```meson
