Merge #19061: doc: Add link to Visual Studio build readme

1c91ffe doc : add link to readme.md in the first section (pad)

Pull request description:

  I have searched how to do it in this doc for some time :-(
  I think it might help other newbies interested in building with visual studio.

ACKs for top commit:
  hebasto:
    ACK 1c91ffe, a new link works as expected :)

Tree-SHA512: 42ef3ba374bced9b4ab0010fe8c30de06f59ff8a84f8e02f8a91f33e7e403cf91d624fc7df3f45096df53171a90b9ff60277969cc30f1357d92094ad72ca9d53

Author: fanquake

doc/build-windows.md

@@ -9,7 +9,7 @@ The options known to work for building Bitcoin Core on Windows are:
 and is the platform used to build the Bitcoin Core Windows release binaries.
 * On Windows, using [Windows
 Subsystem for Linux (WSL)](https://docs.microsoft.com/windows/wsl/about) and the Mingw-w64 cross compiler tool chain.
-* On Windows, using a native compiler tool chain such as [Visual Studio](https://www.visualstudio.com).
+* On Windows, using a native compiler tool chain such as [Visual Studio](https://www.visualstudio.com). See [README.md](/build_msvc/README.md).
 
 Other options which may work, but which have not been extensively tested are (please contribute instructions):