docs: improve enum type for javascript users

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,4 +1,4 @@
-#### Fixes(if relevant): #1
+#### Fixes(if relevant): 
 
 #### Checks
 

README.md

@@ -162,6 +162,14 @@ enum DropPosition {
     inside,
     down,
 }
+// For javascript users, the enum type can not imported from the package,
+// it is just number(0,1,2,3 in order), so you can use this instead:
+const DropPosition = {
+    empty: 0,
+    up: 1,
+    inside: 2,
+    down: 3
+}
 ```
 
 ## event data structure