Microsoft.Extensions.FileSystemGlobbing PACKAGE.md (dotnet#93123)

* Microsoft.Extensions.FileSystemGlobbing PACKAGE.md

Fill out details for `Microsoft.Extensions.FileSystemGlobbing` NuGet
package readme

See dotnet#92228

* Update src/libraries/Microsoft.Extensions.FileSystemGlobbing/src/PACKAGE.md

* Update src/libraries/Microsoft.Extensions.FileSystemGlobbing/src/PACKAGE.md

---------

Co-authored-by: Viktor Hofer <viktor.hofer@microsoft.com>

src/libraries/Microsoft.Extensions.FileSystemGlobbing/src/PACKAGE.md

@@ -2,40 +2,48 @@
 
 <!-- A description of the package and where one can find more documentation -->
 
-
+Provides support for matching file system names/paths using [glob patterns](https://en.wikipedia.org/wiki/Glob_(programming)).
 
 ## Key Features
 
 <!-- The key features of this package -->
 
-*
-*
-*
+* Contains the `Matcher` type, which can be used to match files in the file system based on user-defined patterns.
 
 ## How to Use
 
 <!-- A compelling example on how to use this package with code, as well as any specific guidelines for when to use the package -->
 
+Get all matching files:
+
+```c#
+using Microsoft.Extensions.FileSystemGlobbing;
+
+Matcher matcher = new();
+matcher.AddIncludePatterns(new[] { "*.txt", "*.asciidoc", "*.md" });
+
+string searchDirectory = "../starting-folder/";
+
+IEnumerable<string> matchingFiles = matcher.GetResultsInFullPath(searchDirectory);
+
+// Use matchingFiles if there are any found.
+// The files in this collection are fully qualified file system paths.
+```
+
 ## Main Types
 
 <!-- The main types provided in this library -->
 
 The main types provided by this library are:
 
-* ``
-* ``
-* ``
+* `Microsoft.Extensions.FileSystemGlobbing.Matcher`
 
-## Addtional Documentation
+## Additional Documentation
 
 <!-- Links to further documentation. Remove conceptual documentation if not available for the library. -->
 
-* [Conceptual documentation](https://learn.microsoft.com/en-us/dotnet/standard/serialization/**LIBRARYNAME**/overview)
-* [API documentation](https://learn.microsoft.com/en-us/dotnet/api/**LIBRARYNAME**)
-
-## Related Packages
-
-<!-- The related packages associated with this package -->
+* [Conceptual documentation](https://learn.microsoft.com/en-us/dotnet/core/extensions/file-globbing)
+* [API documentation](https://learn.microsoft.com/dotnet/api/microsoft.extensions.filesystemglobbing)
 
 ## Feedback & Contributing