Editorial: spell cypher as cipher

Matches https://w3c.github.io/webcrypto/Overview.html.

fetch.bs

@@ -261,7 +261,7 @@ means (e.g., <code>data</code> URLs).
 <p class="note no-backref">A <a for=/>response</a> delivered over HTTPS will
 typically have its <a for=response>HTTPS state</a> set to
 "<code>modern</code>". A user agent can use "<code>deprecated</code>" in a transition
-period. E.g., while removing support for a hash function, weak cypher suites, certificates for an
+period. E.g., while removing support for a hash function, weak cipher suites, certificates for an
 "Internal Name", or certificates with an overly long validity period. How exactly a user agent can
 use "<code>deprecated</code>" is not defined by this specification. An
 <a>environment settings object</a> typically derives its