fix: a typo

Author: lidel

README.md

@@ -140,8 +140,8 @@ data.fileSize() // => size in bytes
 #### marshal and unmarshal
 
 ```
-var marsheled = data.marshal()
-var unmarsheled = Unixfs.unmarshal(marsheled)
+var marshaled = data.marshal()
+var unmarshaled = Unixfs.unmarshal(marshaled)
 ```
 
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