doc: note that listening on SIGSEGV & co is unsafe

Note that trying to listen for some signals using `process.on()`
is unsafe in the `process` docs.

PR-URL: https://github.com/nodejs/node/pull/8410
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/process.md

@@ -422,6 +422,11 @@ It is important to take note of the following:
 * `SIGKILL` cannot have a listener installed, it will unconditionally terminate
   Node.js on all platforms.
 * `SIGSTOP` cannot have a listener installed.
+* `SIGBUS`, `SIGFPE`, `SIGSEGV` and `SIGILL`, when not raised artificially
+   using kill(2), inherently leave the process in a state from which it is not
+   safe to attempt to call JS listeners. Doing so might lead to the process
+   hanging in an endless loop, since listeners attached using `process.on()` are
+   called asynchronously and therefore unable to correct the underlying problem.
 
 *Note*: Windows does not support sending signals, but Node.js offers some
 emulation with [`process.kill()`][], and [`ChildProcess.kill()`][]. Sending