Fix vstest integration documentation (#663)

Fix vstest integration documentation

Author: MarcoRossignoli

Documentation/VSTestIntegration.md

@@ -30,7 +30,6 @@ These are a list of options that are supported by coverlet. These can be specifi
 | Option         | Summary                                                                                  |
 |-------------   |------------------------------------------------------------------------------------------|
 |Format          | Coverage output format. These are either cobertura, json, lcov, opencover or teamcity as well as combinations of these formats.   | 
-|MergeWith       | Combine the output of multiple coverage runs into a single result([check the sample](Examples.md)).                       | 
 |Exclude         | Exclude from code coverage analysing using filter expressions.                           | 
 |ExcludeByFile   | Ignore specific source files from code coverage.                                         | 
 |Include         | Explicitly set what to include in code coverage analysis using filter expressions.       | 
@@ -46,8 +45,7 @@ How to specify these options via runsettings?
     <DataCollectors>
       <DataCollector friendlyName="XPlat code coverage">
         <Configuration>
-          <Format>json,cobertura</Format>
-          <MergeWith>/custom/path/result.json</MergeWith>
+          <Format>json,cobertura</Format>          
           <Exclude>[coverlet.*.tests?]*,[*]Coverlet.Core*</Exclude> <!-- [Assembly-Filter]Type-Filter -->
           <Include>[coverlet.*]*,[*]Coverlet.Core*</Include> <!-- [Assembly-Filter]Type-Filter -->
           <ExcludeByAttribute>Obsolete,GeneratedCodeAttribute,CompilerGeneratedAttribute</ExcludeByAttribute>