git tag: mention versionsort.prereleaseSuffix in manpage

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-tag.txt

@@ -98,10 +98,13 @@ OPTIONS
 --sort=<type>::
 	Sort in a specific order. Supported type is "refname"
 	(lexicographic order), "version:refname" or "v:refname" (tag
-	names are treated as versions). Prepend "-" to reverse sort
-	order. When this option is not given, the sort order defaults to the
-	value configured for the 'tag.sort' variable if it exists, or
-	lexicographic order otherwise. See linkgit:git-config[1].
+	names are treated as versions). The "version:refname" sort
+	order can also be affected by the
+	"versionsort.prereleaseSuffix" configuration variable. Prepend
+	"-" to reverse sort order. When this option is not given, the
+	sort order defaults to the value configured for the 'tag.sort'
+	variable if it exists, or lexicographic order otherwise. See
+	linkgit:git-config[1].
 
 --column[=<options>]::
 --no-column::