add plugin version to API

Author: zefir-git

src/main/java/pro/cloudnode/smp/smpcore/Rest.java

@@ -71,6 +71,7 @@ public Rest(final int port) {
 
         javalin.get("/", ctx -> {
             final @NotNull JsonObject obj = new JsonObject();
+            obj.addProperty("version", SMPCore.getInstance().getPluginMeta().getVersion());
             obj.addProperty("time", SMPCore.gameTime().getTime());
             ctx.json(obj);
         });