perf inject: Document missing options

Add the missing --force option to the man page.

Signed-off-by: Sihyeon Jang <uneedsihyeon@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1510842367-11011-1-git-send-email-uneedsihyeon@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-inject.txt

@@ -60,6 +60,10 @@ include::itrace.txt[]
 	found in the jitdumps files captured in the input perf.data file. Use this option
 	if you are monitoring environment using JIT runtimes, such as Java, DART or V8.
 
+-f::
+--force::
+	Don't complain, do it.
+
 SEE ALSO
 --------
 linkperf:perf-record[1], linkperf:perf-report[1], linkperf:perf-archive[1]