perf hists browser: Add missing hotkeys to the help window

The navigation keys were missing (UP, DOWN arrows, etc).

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-3pnln0bws5v0yoqwd3f020nx@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/ui/browsers/hists.c

@@ -887,8 +887,11 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
 		case 'h':
 		case '?':
 			ui__help_window("h/?/F1        Show this window\n"
-					"TAB/UNTAB Switch events\n"
-					"q/CTRL+C  Exit browser\n\n"
+					"UP/DOWN/PGUP\n"
+					"PGDN/SPACE    Navigate\n"
+					"q/ESC/CTRL+C  Exit browser\n\n"
+					"For multiple event sessions:\n\n"
+					"TAB/UNTAB Switch events\n\n"
 					"For symbolic views (--sort has sym):\n\n"
 					"->            Zoom into DSO/Threads & Annotate current symbol\n"
 					"<-            Zoom out\n"