doc: remove minor contradiction in debugger doc

The doc says the debugger is and also isn't full-featured. Even if the
sentences are talking about different things, it's confusing.
`full-featured` seems superfluous in the first sentence anyway, so
remove it. Remove a superfluous `simple` while we're at it.

PR-URL: https://github.com/nodejs/node/pull/9832
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

doc/api/debugger.md

@@ -4,10 +4,10 @@
 
 <!-- type=misc -->
 
-Node.js includes a full-featured out-of-process debugging utility accessible
+Node.js includes an out-of-process debugging utility accessible via a
-via a simple [TCP-based protocol][] and built-in debugging client. To use it,
+[TCP-based protocol][] and built-in debugging client. To use it, start Node.js
-start Node.js with the `debug` argument followed by the path to the script to
+with the `debug` argument followed by the path to the script to debug; a prompt
-debug; a prompt will be displayed indicating successful launch of the debugger:
+will be displayed indicating successful launch of the debugger:
 
 ```txt
 $ node debug myscript.js