Refine diagnostic link warning message for clarity.

The warning message now clearly indicates the unresolved URL and missing file path when creating an auto text link. This improves readability and helps users better understand the issue during debugging.

Author: Mpdreamz

src/Elastic.Markdown/Myst/InlineParsers/DiagnosticLinkInlineParser.cs

@@ -119,7 +119,7 @@ public override bool Match(InlineProcessor processor, ref StringSlice slice)
 				processor.EmitWarning(line,
 					column,
 					length,
-					$"Can not create an auto title link to '{file.FullName}' however this file can not be resolved.");
+					$"'{url}' could not be resolved to a markdown file while creating an auto text link, '{file.FullName}' does not exist.");
 			}
 
 			var title = markdown?.Title;