Update usage docs and changelog.

Changes.mdown

@@ -2,6 +2,9 @@
 -----
 Release date: **not yet**
 
+* `git flow feature finish` can now be called without a feature branch
+  name(prefix) argument and will finish the current branch, if on any.
+
 * Various minor bug fixes related to internal argument passing
 
 0.4.1:

git-flow-feature

@@ -44,7 +44,7 @@ PREFIX=$(git config --get gitflow.prefix.feature)
 usage() {
 	echo "usage: git flow feature [list] [-v]"
 	echo "       git flow feature start [-F] <name> [<base>]"
-	echo "       git flow feature finish [-rFk] <name|nameprefix>"
+	echo "       git flow feature finish [-rFk] [<name|nameprefix>]"
 	echo "       git flow feature publish <name>"
 	echo "       git flow feature track <name>"
 	echo "       git flow feature diff [<name|nameprefix>]"