add space after period (dotnet#5238)

Author: boltomli

xml/System.Speech.Synthesis/SpeechSynthesizer.xml

@@ -153,7 +153,7 @@ namespace SampleSynthesis
   
  Pronunciations specified in an external lexicon file take precedence over the pronunciations of the speech synthesizer's internal lexicon or dictionary. However, pronunciations specified inline in prompts created with any of the <xref:System.Speech.Synthesis.PromptBuilder.AppendTextWithPronunciation%2A>, <xref:System.Speech.Synthesis.PromptBuilder.AppendSsmlMarkup%2A>, or <xref:System.Speech.Synthesis.PromptBuilder.AppendSsml%2A> methods take precedence over pronunciations specified in any lexicon. Inline pronunciations apply only to a single occurrence of a word. See [Lexicons and Phonetic Alphabets](https://docs.microsoft.com/previous-versions/office/developer/speech-technologies/hh378335(v%3doffice.14)) for more information.  
   
- You can add multiple lexicons to a <xref:System.Speech.Synthesis.SpeechSynthesizer> object.Two values are currently supported for the `mediaType` parameter:  
+ You can add multiple lexicons to a <xref:System.Speech.Synthesis.SpeechSynthesizer> object. Two values are currently supported for the `mediaType` parameter:  
   
 -   The value `application/pls+xml` indicates that the lexicon conforms to the [Pronunciation Lexicon Specification (PLS) Version 1.0](https://go.microsoft.com/fwlink/?LinkId=201766). This is the preferred format to use.