Update speech-ssml-phonetic-sets.md

Author: sally-baolian

articles/cognitive-services/Speech-Service/speech-ssml-phonetic-sets.md

@@ -20,8 +20,8 @@ Speech service supports the [International Phonetic Alphabet (IPA)](https://en.w
 
 |`ipa` | Symbol         | Note|
 |-------|-------------------|-------------------|
-| `ˈ`   | Primary stress     |  Don’t use single quote (‘ or ') though it looks similar.  |
-| `ˌ`   | Secondary stress   | Don’t use comma (,) though it looks similar.                 |
+| `ˈ`   | Primary stress     |  Don’t use single quote ( ‘ or ' ) though it looks similar.  |
+| `ˌ`   | Secondary stress   | Don’t use comma ( , ) though it looks similar.                 |
 | `.`   | Syllable boundary  |                  |
 | `ː`   | Long  | Don’t use colon ( : or ：) though it looks similar.         |
 | `‿`   | Linking   |           |