Add/fix repo links for BA sources.

Author: barnson

src/Docusaurus/docs/fivefour/oopbas.md

@@ -6,6 +6,10 @@ The rest of this document details changes required to update custom bootstrapper
 
 The motivation for this change can be found in [#7916](https://github.com/wixtoolset/issues/issues/7916). This is obviously a significant breaking change so it was also taken as an opportunity to improve several .nupkg package names as described in [#8020](https://github.com/wixtoolset/issues/issues/8020).
 
+:::tip
+The [WiX repo on GitHub](https://github.com/wixtoolset/wix) contains the code to bootstrapper applications using the new model, like [WixStandardBootstrapperApplication](https://github.com/wixtoolset/wix/blob/HEAD/src/ext/Bal/stdbas/WixStandardBootstrapperApplication.cpp) (C++) and [WixBA](https://github.com/wixtoolset/wix/tree/HEAD/src/test/burn/WixToolset.WixBA) (C#).
+:::
+
 First, the custom bootstrapper application project needs to change from DLL to EXE.
 
 ```diff

src/Docusaurus/docs/fourthree/faqs.md

@@ -277,9 +277,9 @@ Note that Microsoft chose a confusing naming convention for newer versions of .N
 To use a BA written in .NET 6+, use `bal:WixDotNetCoreBootstrapperApplicationHost` instead of `bal:WixManagedBootstrapperApplicationHost`.
 .NET 5 and earlier versions are not supported because they were already at end of life when v4 shipped.
 
-Even though the WixBA is not currently shipping, it is still available at https://github.com/wixtoolset/wix4/tree/develop/src/test/burn/WixToolset.WixBA.
+Even though the WixBA is not currently shipping, it is still available at https://github.com/wixtoolset/wix4/tree/HEAD/src/test/burn/WixToolset.WixBA.
 You can basically see a step-by-step example of upgrading a v3 MBA by looking at the history of that folder and `WixToolset.WixBA.csproj`.
-Another folder that might be useful is https://github.com/wixtoolset/wix4/tree/develop/src/test/burn/TestData/TestBA.
+Another folder that might be useful is https://github.com/wixtoolset/wix4/tree/HEAD/src/test/burn/TestData/TestBA.
 
 In v3, MBAs needed to be built against the same version of `BootstrapperCore.dll` as the bundle.
 They didn't need to include it as a payload because the Bal WiX extension automatically added it.