doc: add abnormal termination step 1

Confirming if the process was exited for proactive invocation of `process.exit`.

documentation/abnormal_termination/step1/using_exit_stack_traces.md

@@ -1 +1,15 @@
-//TODO
+# Using `--trace-exit` CLI Option
+
+`--trace-exit` CLI option would print a stack trace on every proactive `process.exit`
+invocation. It is convenient to confirm if the abnormal exit of the process was
+initiated from an invocation of `process.exit` or something other crashes.
+
+## How To
+
+```bash
+> node --trace-exit src/abnormal-exit.js
+```
+
+## Useful Links
+
+- https://nodejs.org/docs/latest/api/cli.html#cli_trace_exit