doc: fix typo in path doc

PR-URL: https://github.com/nodejs/node/pull/8527
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/path.md

@@ -279,7 +279,7 @@ added: v0.1.16
 
 * `...paths` {String} A sequence of path segments
 
-The `path.join()` method join all given `path` segments together using the
+The `path.join()` method joins all given `path` segments together using the
 platform specific separator as a delimiter, then normalizes the resulting path.
 
 Zero-length `path` segments are ignored. If the joined path string is a