Fixed typo: seeked -> sought

Author: ss18

Doc/library/io.rst

@@ -318,7 +318,7 @@ I/O Base Classes
    This class provides empty abstract implementations for many methods
    that derived classes can override selectively; the default
    implementations represent a file that cannot be read, written or
-   seeked.
+   sought.
 
    Even though :class:`IOBase` does not declare :meth:`read`
    or :meth:`write` because their signatures will vary, implementations and