Grammatical correction for doc clarity

Build/Chakra.Build.props

@@ -47,7 +47,7 @@
         GLOBAL_ENABLE_WRITE_BARRIER=1
       </PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(NTDDIVersion)'!=''" >%(PreprocessorDefinitions);NTDDI_VERSION=$(NTDDIVersion)</PreprocessorDefinitions>
-      <!-- REVIEW: These are warning are introduced when moving to VS2015 tools, may want to clean these up -->
+      <!-- REVIEW: These warnings are introduced when moving to VS2015 tools, may want to clean these up -->
       <DisableSpecificWarnings>
         %(DisableSpecificWarnings);
         4458;     <!-- declaration of '' hides class member -->