logcat: -v thread help missing

KISS documentation for -v thread added

Test: manual logcat -v --help
Bug: 37030280
Change-Id: If1ad9d3862a68dfe570b524c36efd4fae5b03262
diff --git a/logcat/logcat.cpp b/logcat/logcat.cpp
index 64d1d2f..e9ef9cc 100644
--- a/logcat/logcat.cpp
+++ b/logcat/logcat.cpp
@@ -530,6 +530,7 @@
         "  process    — Display PID only.\n"
         "  raw        — Display the raw log message, with no other metadata fields.\n"
         "  tag        — Display the priority/tag only.\n"
+        "  thread     — Display priority, PID and TID of process issuing the message.\n"
         "  threadtime — Display the date, invocation time, priority, tag, and the PID\n"
         "               and TID of the thread issuing the message. (the default format).\n"
         "  time       — Display the date, invocation time, priority/tag, and PID of the\n"