pg_test_timing: add page (#18481)

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

Author: fabioperrella

pages/common/pg_test_timing.md

@@ -0,0 +1,12 @@
+# pg_test_timing
+
+> Measure timing overhead on your system (ensure clock monotonicity).
+> More information: <https://www.postgresql.org/docs/current/pgtesttiming.html>.
+
+- Run the default timing test (3 seconds):
+
+`pg_test_timing`
+
+- Run for a custom duration:
+
+`pg_test_timing {{[-d|--duration]}} {{seconds}}`