doc: fix typo in doc/repl.md line: 6

fix doc/api/repl.md line 6 "includable" => "includible"

Fixes: https://github.com/nodejs/code-and-learn/issues/58
PR-URL: https://github.com/nodejs/node/pull/9582
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Shigeki Ohtsu <ohtsu@ohtsu.org>

doc/api/repl.md

@@ -3,7 +3,7 @@
 > Stability: 2 - Stable
 
 The `repl` module provides a Read-Eval-Print-Loop (REPL) implementation that
-is available both as a standalone program or includable in other applications.
+is available both as a standalone program or includible in other applications.
 It can be accessed using:
 
 ```js