winbuild/README: document how to clean a build

- Add a new section explaining that a build can be cleaned by adding the
  keyword "clean" to the build command.

- Add an example of using the "x64 Native Tools" prompt to the VS
  command prompt section.

- Update the Legacy Windows section's lack-of-cipher support warning to
  say "Windows 8 and earlier" instead of "Windows XP and earlier".

Ref: https://github.com/curl/curl/discussions/15277

Closes https://github.com/curl/curl/pull/15291

diff --git a/winbuild/README.md b/winbuild/README.md
index 594089052f0b52e59f40caeb9134f4ccfa2f582b..541128d92a7401ac19c00b1f58d57e0df8fa48c2 100644 (file)
--- a/winbuild/README.md
+++ b/winbuild/README.md
@@ -60,7 +60,8 @@ Open a Visual Studio Command prompt:
  Using the **'VS [version] [platform] [type] Command Prompt'** menu entry:\r
  where [version] is the Visual Studio version, [platform] is e.g. x64 and\r
  [type] Native of Cross platform build. This type of command prompt may not\r
- exist in all Visual Studio versions.\r
+ exist in all Visual Studio versions. For example, to build a 64-bit curl open\r
+ the x64 Native Tools prompt.\r
 \r
  See also: [Set the Path and Environment Variables for Command-Line Builds](https://docs.microsoft.com/en-us/cpp/build/building-on-the-command-line)\r
 \r
@@ -113,6 +114,17 @@ where `<options>` is one or many of:
  - `SSL_PATH=<path>`             - Custom path for OpenSSL\r
  - `ZLIB_PATH=<path>`            - Custom path for zlib\r
 \r
+## Cleaning a build\r
+\r
+ For most build configurations you can remove a bad build by using the same\r
+ options with the added keyword "clean". For example:\r
+\r
+    nmake /f Makefile.vc mode=static clean\r
+\r
+ Build errors due to switching Visual Studio platform tools or mistakenly\r
+ specifying the wrong machine platform for the tools can usually be solved by\r
+ first cleaning the bad build.\r
+\r
 ## Static linking of Microsoft's C runtime (CRT):\r
 \r
  If you are using mode=static nmake will create and link to the static build\r
@@ -193,7 +205,7 @@ where `<options>` is one or many of:
 \r
  When you build curl using the build files in this directory the default SSL\r
  backend will be Schannel (Windows SSPI), the native SSL library that comes\r
- with the Windows OS. Schannel in Windows <= XP is not able to connect to\r
- servers that no longer support the legacy handshakes and algorithms used by\r
+ with the Windows OS. Schannel in Windows 8 and earlier is not able to connect\r
+ to servers that no longer support the legacy handshakes and algorithms used by\r
  those versions. If you will be using curl in one of those earlier versions of\r
  Windows you should choose another SSL backend like OpenSSL.\r