xev: add page (#6548)

pages/common/xev.md

@@ -0,0 +1,20 @@
+# xev
+
+> Print contents of X events.
+> More information: <https://gitlab.freedesktop.org/xorg/app/xev>.
+
+- Monitor all occuring X events:
+
+`xev`
+
+- Monitor all X events of the root window instead of creating a new one:
+
+`xev -root`
+
+- Monitor all X events of a particular window:
+
+`xev -id {{window_id}}`
+
+- Monitor X events from a given category (can be specified multiple times):
+
+`xev -event {{event_category}}`