Update: README.md

README.md

 ```
 
 #### Input
+Please note that the input file is in JSON format.
+
 ```Json
 {
-    "sample_id": "sample_id",
-    "INPUT": [
-		"file_1",
-		"file_2",
-		"file_3",
-		...,
-		"file_n"]
+  "sample_id": "sample_id",
+  "INPUT": [
+    "file_1",
+    "file_2",
+    "file_3",
+    ...,
+    "file_n"]
 }
 ```