Update manifest.xml (#93)

Changing taskpane.html to index.html (see #88 )

It should technically make no difference as the projects seems to be rerouted to index.html anyway but formally the OP of #88 is right and the project does not have a taskpane.html

Author: aafvstam

Samples/Office.ASP.NETCoreReactAddins/excel-js/manifest.xml

@@ -16,7 +16,7 @@
     <Host Name="Workbook"/>
   </Hosts>
   <DefaultSettings>
-    <SourceLocation DefaultValue="~remoteAppUrl/taskpane.html"/>
+    <SourceLocation DefaultValue="~remoteAppUrl/index.html"/>
   </DefaultSettings>
   <Permissions>ReadWriteDocument</Permissions>
   <VersionOverrides xmlns="http://schemas.microsoft.com/office/taskpaneappversionoverrides" xsi:type="VersionOverridesV1_0">
@@ -69,7 +69,7 @@
       <bt:Urls>
         <bt:Url id="GetStarted.LearnMoreUrl" DefaultValue="https://go.microsoft.com/fwlink/?LinkId=276812" />
         <bt:Url id="Commands.Url" DefaultValue="~remoteAppUrl/commands.html" />
-        <bt:Url id="Taskpane.Url" DefaultValue="~remoteAppUrl/taskpane.html" />
+        <bt:Url id="Taskpane.Url" DefaultValue="~remoteAppUrl/index.html" />
       </bt:Urls>
       <bt:ShortStrings>
         <bt:String id="GetStarted.Title" DefaultValue="Get started with your sample add-in!" />
@@ -82,4 +82,4 @@
       </bt:LongStrings>
     </Resources>
   </VersionOverrides>
-</OfficeApp>
+</OfficeApp>