Documentation: hash-object.

The file parameter is better spelled just "file", not "any file
on the filesystem".  We stress that in the description text
later anyway.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Documentation/git-hash-object.txt

@@ -8,7 +8,7 @@ git-hash-object - Computes object ID and optionally creates a blob from a file.
 
 SYNOPSIS
 --------
-'git-hash-object' [-t <type>] [-w] <any-file-on-the-filesystem>
+'git-hash-object' [-t <type>] [-w] <file>
 
 DESCRIPTION
 -----------