perf script: Fix reference to perf insert instead of perf inject

perf script: Fix reference to perf insert instead of perf inject

Amend "perf insert" to "perf inject".

Fixes: 05e02c8febc9b391 ("perf script: Add machine_pid and vcpu")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20220809123258.9086-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>