git-hash-object.txt: document --literally option

Document the git-hash-object --literally option added by 5ba9a93
(hash-object: add --literally option, 2014-09-11).

While here, also correct a minor typesetting oversight.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-hash-object.txt

@@ -9,7 +9,7 @@ git-hash-object - Compute object ID and optionally creates a blob from a file
 SYNOPSIS
 --------
 [verse]
-'git hash-object' [-t <type>] [-w] [--path=<file>|--no-filters] [--stdin] [--] <file>...
+'git hash-object' [-t <type>] [-w] [--path=<file>|--no-filters] [--stdin [--literally]] [--] <file>...
 'git hash-object' [-t <type>] [-w] --stdin-paths [--no-filters] < <list-of-paths>
 
 DESCRIPTION
@@ -51,7 +51,13 @@ OPTIONS
 	Hash the contents as is, ignoring any input filter that would
 	have been chosen by the attributes mechanism, including the end-of-line
 	conversion. If the file is read from standard input then this
-	is always implied, unless the --path option is given.
+	is always implied, unless the `--path` option is given.
+
+--literally::
+	Allow `--stdin` to hash any garbage into a loose object which might not
+	otherwise pass standard object parsing or git-fsck checks. Useful for
+	stress-testing Git itself or reproducing characteristics of corrupt or
+	bogus objects encountered in the wild.
 
 GIT
 ---