MINOR: [Docs] Add note to Windows docs about patch util (#47839)

### Rationale for this change

For certain C++ build configurations, we require `patch` to be in the user's `PATH`. This was introduced in e1f727c and a [Discussion pointed this out](#47829 (reply in thread)). For Linux and macOS, it's pretty reasonable for us to assume `patch` is available but not on Windows.

### What changes are included in this PR?

Adds a note in the "Debug" section of the Windows docs.

### Are these changes tested?

Yes, I'll add a screenshot to make review easier.

### Are there any user-facing changes?

No.

Authored-by: Bryce Mecum <[email protected]>
Signed-off-by: AlenkaF <[email protected]>

Author: amoeba

docs/source/developers/cpp/windows.rst

@@ -327,6 +327,12 @@ The command line to build Arrow in Debug mode will look something like this:
          -DBOOST_LIBRARYDIR=C:/local/boost_1_63_0/lib64-msvc-14.0
    cmake --build . --config Debug
 
+Depending on the CMake variables or preset you use, you may need to have the
+``patch`` utility in your ``PATH``. There are a number of ways to do this. For
+example, if you're already using  `Git for Windows
+<https://git-scm.com/downloads/win>`_, you could add ``C:\Program
+Files\Git\usr\bin`` to your ``PATH``.
+
 Windows dependency resolution issues
 ====================================