Support jpkl executable for Windows (#872)

This updates the script used to start the executable to support
Windows as well.

For Windows support, the executable needs to be named `jpkl.bat`.

docs/modules/pkl-cli/pages/index.adoc

@@ -53,8 +53,7 @@ whereas, the Alpine Linux executable is statically linked against _musl libc_ an
 ====
 
 The Java executable works on multiple platforms and has a smaller binary size than the native executables.
-However, it requires a Java 17 (or higher) runtime on the system path, has a noticeable startup delay,
-and runs complex Pkl code slower than the native executables.
+However, it requires a Java 17 (or higher) runtime on the system path, and has a noticeable startup delay.
 
 All flavors are built from the same codebase and undergo the same automated testing.
 Except where noted otherwise, the rest of this page discusses the native executables.
@@ -201,6 +200,14 @@ NOTE: We currently do not support the aarch64 architecture for Windows.
 [[java-executable]]
 === Java Executable
 
+The Java executable is a jar that can be executed directly on macOS, Linux, and Windows.
+
+It requires `java` to be installed, and available on `$PATH`.
+
+[tabs]
+====
+macOS/Linux::
++
 [source,shell]
 [subs="+attributes"]
 ----
@@ -209,6 +216,16 @@ chmod +x jpkl
 ./jpkl --version
 ----
 
+Windows::
++
+[source,PowerShell]
+[subs="+attributes"]
+----
+Invoke-WebRequest '{uri-pkl-java-download}' -OutFile jpkl.bat
+.\jpkl --version
+----
+====
+
 This should print something similar to:
 
 [source,shell]
@@ -217,8 +234,7 @@ This should print something similar to:
 Pkl {pkl-version} (macOS 14.2, Java 17.0.10)
 ----
 
-NOTE: The Java executable does not work as an executable file on Windows.
-However, it will work as a jar, for example, with `java -jar jpkl`.
+NOTE: The Java executable is named `jpkl`.
 
 [[usage]]
 == Usage
@@ -721,8 +737,6 @@ Type :help or :examples for more information.
 pkl>
 ----
 
-NOTE: The Java executable is named `jpkl`.
-
 === Loading Modules
 
 To load <<config.pkl,`config.pkl`>> into the REPL, run: