doc: make execFileSync in line with execFile
doc: make execFileSync in line with execFile

PR-URL: https://github.com/nodejs/node/pull/2940
Reviewed-By: Michaël Zasso <dc852f7f42c586356f6be32b8780273088b3bded@gmail.com>
Reviewed-By: Roman Reiss <b1c1d8736f20db3fb6c1c66bb1455ed43909f0d8@silverwind.io>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node