Improve glob handling for source paths and update docs

- Simplify glob handling in TailwindCSSBuildPlugin to support **
patterns - Update README and Tailwind.css example to clarify glob usage
- Add Template.swift example using Tailwind classes - Extend tests to
verify class extraction from globbed Swift files

Tests/SwiftTailwindTests/Tests.swift

@@ -17,6 +17,10 @@ struct SwiftTailwindExampleTests {
       generatedCSS?.contains("text-\\[\\#f05138\\]") == true,
       "Arbitary value class used in Test.html is generated."
     )
+    #expect(
+      generatedCSS?.contains("bg-red-100") == true,
+      "Arbitary value class used in Folder/Template.swift is generated."
+    )
     #expect(
       generatedCSS?.contains("bg-blue-500") == false,
       "Class not used is not generated."