Add support for <?xsl-output default="path"?>

Author: clovett

docs/help/xslt.md

@@ -1,8 +1,9 @@
 ## XSLT Transformation
 
-The `XSL Output` tab on the main window provides a rendering of the XSLT
-output from the specified XSLT stylesheet.  XSLT stylesheets can be referenced
-in the XML document using this syntax, as shown in the `hamlet.xml` sample.
+The `XSL Output` tab on the main window provides a rendering of the
+XSLT output from the specified XSLT stylesheet.  XSLT stylesheets can
+be referenced in the XML document using this syntax, as shown in the
+`hamlet.xml` sample.
 
 ```xml
 <?xml-stylesheet type="text/xsl" href="willy.xsl"?>
@@ -13,14 +14,28 @@ in the XML document using this syntax, as shown in the `hamlet.xml` sample.
 You can also enter your own XSLT file name on this tab by changing the
 contents of the XSLT Location field at the top of the XSLT output tab.
 
-By default the HTML output is written to your system `%TEMP%` folder
-but you can change that in the Output: text box.
+By default the HTML output is written to the same folder that contains
+your XML file, but if that folder is not writable it writes to that
+folder it will use your system `%TEMP%` folder.
 
-If you modify the XML or XSLT file you can press the `Transform` button
-to perform another XSLT transformation and the changes will be rendered.
+You can customize the default output file name by adding the following
+additional processing instruction to your XML document:
 
-This tab supports 2 different web browser engines.  The original WinForms
-web browser and the new Chromium based WebView2.  The new WebView2 control
-is much faster on large XSLT outputs.
+```xml
+<?xsl-output default="hamlet"?>
+```
+
+Then depending on the `<?xsl-output method="..."` the appropriate file
+extension will be added.  You can also override this by directly
+editing the Output: text box.  If you modify the XML or XSLT file you
+can press the `Transform` button to perform another XSLT
+transformation and the changes will be rendered.
+
+This tab supports 2 different web browser engines.  The original
+WinForms web browser and the new Chromium based WebView2.  The new
+WebView2 control is much faster on large XSLT outputs.
 
-XML Notepad does not automatically install this new WebView2 component.  Please see [Microsoft Edge WebView2](https://docs.microsoft.com/en-us/DeployOffice/webview2-install) for information on how to install this optional component.
+XML Notepad does not automatically install this new WebView2
+component.  Please see [Microsoft Edge
+WebView2](https://docs.microsoft.com/en-us/DeployOffice/webview2-install)
+for information on how to install this optional component.