feature (static): upate a few static pages

- /about now shows a list of installed plugin
- 404 page is more "funky"

server/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	_ "embed"
 	"fmt"
 	"github.com/gorilla/mux"
 	. "github.com/mickael-kerjean/filestash/server/common"
@@ -15,6 +16,9 @@ import (
 	"strconv"
 )
 
+//go:embed plugin/index.go
+var EmbedPluginList []byte
+
 func main() {
 	app := App{}
 	Init(&app)
@@ -125,6 +129,10 @@ func Init(a *App) {
 		Log.Warning("No starter plugin available")
 		return
 	}
+
+	go func() {
+		InitPluginList(EmbedPluginList)
+	}()
 	select {}
 }