Update speech-synthesis-markup.md

update the document by adding a link to explain UPS in TTS SSML

Author: MelindaAnxin

articles/cognitive-services/Speech-Service/speech-synthesis-markup.md

@@ -325,7 +325,7 @@ Phonetic alphabets are composed of phones, which are made up of letters, numbers
 
 | Attribute | Description | Required / Optional |
 |-----------|-------------|---------------------|
-| `alphabet` | Specifies the phonetic alphabet to use when synthesizing the pronunciation of the string in the `ph` attribute. The string specifying the alphabet must be specified in lowercase letters. The following are the possible alphabets that you may specify.<ul><li>`ipa` &ndash; <a href="https://en.wikipedia.org/wiki/International_Phonetic_Alphabet" target="_blank">International Phonetic Alphabet <span class="docon docon-navigate-external x-hidden-focus"></span></a></li><li>`sapi` &ndash; [Speech service phonetic alphabet](speech-ssml-phonetic-sets.md)</li><li>`ups` &ndash; Universal Phone Set</li></ul><br>The alphabet applies only to the `phoneme` in the element.. | Optional |
+| `alphabet` | Specifies the phonetic alphabet to use when synthesizing the pronunciation of the string in the `ph` attribute. The string specifying the alphabet must be specified in lowercase letters. The following are the possible alphabets that you may specify.<ul><li>`ipa` &ndash; <a href="https://en.wikipedia.org/wiki/International_Phonetic_Alphabet" target="_blank">International Phonetic Alphabet <span class="docon docon-navigate-external x-hidden-focus"></span></a></li><li>`sapi` &ndash; [Speech service phonetic alphabet](speech-ssml-phonetic-sets.md)</li><li>`ups` &ndash;<a href="https://documentation.help/Microsoft-Speech-Platform-SDK-11/17509a49-cae7-41f5-b61d-07beaae872ea.htm" target="_blank"> Universal Phone Set</a></li></ul><br>The alphabet applies only to the `phoneme` in the element.. | Optional |
 | `ph` | A string containing phones that specify the pronunciation of the word in the `phoneme` element. If the specified string contains unrecognized phones, the text-to-speech (TTS) service rejects the entire SSML document and produces none of the speech output specified in the document. | Required if using phonemes. |
 
 **Examples**