Updated Filer Server API (markdown)

Filer-Server-API.md

@@ -125,11 +125,18 @@ Seaweed-Some: some string value
 ...
 # delete all "Seaweed-" prefixed meta data
 curl -X DELETE http://localhost:8888/path/to/a/file?tagging
+# delete specific "Seaweed-" prefixed meta data
+curl -X DELETE http://localhost:8888/path/to/a/file?tagging=Name1,Some
+
 ```
 | Method | Request | Header | Operation |
 | ---- | ---- | -- | -- |
 | PUT | <file_url>?tagging | Prefixed with "Seaweed-" | set the meta data  |
 | DELETE | <file_url>?tagging |  | remove all the "Seaweed-" prefixed header  |
+| DELETE | <file_url>?tagging=Some,Name |  | remove the headers "Seaweed-Some", "Seaweed-Name" |
+
+Notice that the tag names follow http header key convention, with the first character capitalized.
+
 ### Create an empty folder
 Folders usually are created automatically when uploading a file. To create an empty file, you can use this:
 ```