doc: fix documentation of process.argv

The current documentation states that if run something like
`node app.js` then in our process.argv array first elements is `node`,
but actually it's `process.execPath` not `node`
as documentation currently suggests.

Fixes: https://github.com/nodejs/node/issues/7434
PR-URL: https://github.com/nodejs/node/pull/7449
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/process.md

@@ -450,10 +450,11 @@ console.log(`This processor architecture is ${process.arch}`);
 added: v0.1.27
 -->
 
-The `process.argv` property returns a array containing the command line
+The `process.argv` property returns an array containing the command line
 arguments passed when the Node.js process was launched. The first element will
-be 'node', the second element will be the name of the JavaScript file. The
+be [`process.execPath`]. The second element will be the path to the
-remaining elements will be any additional command line arguments.
+JavaScript file being executed. The remaining elements will be any additional
+command line arguments.
 
 For example, assuming the following script for `process-args.js`:
 
@@ -473,7 +474,7 @@ $ node process-2.js one two=three four
 Would generate the output:
 
 ```text
-0: node
+0: /usr/local/bin/node
 1: /Users/mjr/work/node/process-2.js
 2: one
 3: two=three
@@ -1663,6 +1664,7 @@ cases:
 [`process.argv`]: #process_process_argv
 [`process.exit()`]: #process_process_exit_code
 [`process.kill()`]: #process_process_kill_pid_signal
+[`process.execPath`]: #process_process_execPath
 [`promise.catch()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/catch
 [`require.main`]: modules.html#modules_accessing_the_main_module
 [`setTimeout(fn, 0)`]: timers.html#timers_settimeout_callback_delay_arg