new-style documentation for most commands

libexec/rbenv-hooks

@@ -1,4 +1,7 @@
 #!/usr/bin/env bash
+# Summary: List hook scripts for a rbenv command
+# Usage: rbenv hooks COMMAND
+
 set -e
 [ -n "$RBENV_DEBUG" ] && set -x
 
@@ -12,7 +15,7 @@ fi
 
 RBENV_COMMAND="$1"
 if [ -z "$RBENV_COMMAND" ]; then
-  echo "usage: rbenv hooks COMMAND" >&2
+  rbenv-help --usage hooks >&2
   exit 1
 fi