Add a more detailed usage note, and use logrus

Signed-off-by: Izuru Yakumo <yakumo.izuru@chaotic.ninja>

git-svn-id: file:///srv/svn/repo/aya/trunk@59 cec141ff-132a-4243-88a5-ce187bd62f94

cmd/aya/main.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
-	"log"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -16,6 +15,7 @@ import (
 	"github.com/russross/blackfriday/v2"
 	"gopkg.in/yaml.v2"
 	"marisa.chaotic.ninja/aya"
+	log "github.com/sirupsen/logrus"
 )
 
 const (
@@ -303,10 +303,22 @@ func init() {
 	os.Setenv("PATH", p)
 }
 
+func printUsage() {
+	fmt.Printf("%v <command> [args]\n", os.Args[0])
+	fmt.Printf("\n")
+	fmt.Printf("Where <command> is:\n")
+	fmt.Printf("\tbuild\tGenerate site\n")
+	fmt.Printf("\twatch\t(Re)generate site while looking for changes\n")
+	fmt.Printf("\tvar\tQuery a variable from a markdown file\n")
+	fmt.Printf("\tversion\tPrint version and exit\n")
+	fmt.Printf("\n")
+	fmt.Printf("Other commands may be dynamically added by plugins found in %v\n", AYADIR)
+	os.Exit(0)
+}
+
 func main() {
 	if len(os.Args) == 1 {
-		fmt.Println(os.Args[0], "<command> [args]")
-		return
+		printUsage()
 	}
 	cmd := os.Args[1]
 	args := os.Args[2:]