doc: fix spelling mistake in node.js comment

Per: https://github.com/joyent/node/pull/8876

PR-URL: https://github.com/nodejs/node/pull/2391
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Roman Reiss <me@silverwind.io>

src/node.js

@@ -277,7 +277,7 @@
     process._tickDomainCallback = _tickDomainCallback;
 
     // This tickInfo thing is used so that the C++ code in src/node.cc
-    // can have easy accesss to our nextTick state, and avoid unnecessary
+    // can have easy access to our nextTick state, and avoid unnecessary
     // calls into JS land.
     const tickInfo = process._setupNextTick(_tickCallback, _runMicrotasks);