Remove superfluous text in the HKDF derive bits operation (#372)

Author: twiss

spec/Overview.html

@@ -13055,16 +13055,7 @@ <h4>Operations</h4>
                 </li>
                 <li>
                   <p>
-                    Let |extractKey| be a key equal to |n| zero bits where
-                    |n| is the size of the output of the hash function described by the
-                    {{HkdfParams/hash}} member of
-                    |normalizedAlgorithm|.
-                  </p>
-                </li>
-                <li>
-                  <p>
-                    Let |keyDerivationKey| be the secret represented by {{CryptoKey/[[handle]]}} internal slot of |key|
-                    as the message.
+                    Let |keyDerivationKey| be the secret represented by {{CryptoKey/[[handle]]}} internal slot of |key|.
                   </p>
                 </li>
                 <li>