Updated Filer JWT Use (markdown)

Filer-JWT-Use.md

@@ -1,3 +1,7 @@
+## Introduction
+
+See [the security overview](https://github.com/seaweedfs/seaweedfs/wiki/Security-Overview#securing-filer-http-with-jwt) for a more complete description.
+
 ## How to get a valid JWT
 
 The Filer won't generate JWTs, you will have to configure another service to create a JWT with the same signing key set in the `security.toml` file described on the Security Configuration wiki page. When generating the JWT, ensure that the timeout in seconds matches the timeout set in the `security.toml` file.
@@ -9,3 +13,5 @@ The Filer supports receiving a JWT in three different forms:
 1. Through the `Authorization: Bearer <token>` header
 2. Via the request's query parameters: http://localhost:8888/buckets/all?jwt=token
 3. In an HTTP-only cookie named AT(Access Token)
+
+