Merge pull request #457 from jwilk/spelling

Remove duplicated words and add missing commas

draft-ietf-tls-tls13.md

@@ -1659,7 +1659,7 @@ its own ServerHello which indicates the negotiated connection parameters. [{{ser
 The combination of the ClientHello and the ServerHello determines
 the values of ES and SS, as described above. If either a pure
 (EC)DHE or (EC)DHE-PSK cipher suite is in use, then the ServerHello
-will will contain a "key_share" extension with the server's ephemeral
+will contain a "key_share" extension with the server's ephemeral
 Diffie-Hellman share which MUST be in the same group.
 If a pure PSK or an (EC)DHE-PSK cipher suite is negotiated, then the
 ServerHello will contain a "pre_shared_key" extension indicating
@@ -1686,7 +1686,7 @@ Certificate
 : the certificate of the endpoint. This message is omitted if the
   server is not authenticating with a certificate (i.e.,
   with PSK or (EC)DHE-PSK cipher suites). Note that if raw public keys
-  {{RFC7250}} or or the cached information extension
+  {{RFC7250}} or the cached information extension
   {{?I-D.ietf-tls-cached-info}} are in use, then this message
   will not contain a certificate but rather some other value
   corresponding to the server's long-term key.
@@ -2013,7 +2013,7 @@ bytes of their Random value to the bytes:
 TLS 1.3 clients receiving a TLS 1.2 or below ServerHello MUST check
 that the top eight octets are not equal to either of these values. TLS
 1.2 clients SHOULD also perform this check if the ServerHello
-indicates TLS 1.1 or below. If a match is found the client MUST abort
+indicates TLS 1.1 or below. If a match is found, the client MUST abort
 the handshake with a fatal "illegal_parameter" alert. This mechanism
 provides limited protection against downgrade attacks over and above
 that provided by the Finished exchange: because the ServerKeyExchange
@@ -2734,7 +2734,7 @@ and is more easily extensible in the handshake state machine.
 
 #### Early Data Indication
 
-When PSK resumption is used the the client can send application data
+When PSK resumption is used, the client can send application data
 in its first flight of messages. If the client opts to do so, it MUST
 supply an "early_data" extension as well as the "pre_shared_key"
 extension.