Add django-block-fragments to template-fragments essay (#3227)

Author: medihack

www/content/essays/template-fragments.md

@@ -160,6 +160,7 @@ Here are some known implementations of the fragment concept:
   * [chameleon_partials package](https://github.com/mikeckennedy/chameleon_partials)
   * [htmlgenerator](https://github.com/basxsoftwareassociation/htmlgenerator)
   * [django-template-partials](https://pypi.org/project/django-template-partials/) ([repository](https://github.com/carltongibson/django-template-partials))
+  * [django-block-fragments](https://github.com/medihack/django-block-fragments)
 * .NET
   * [Giraffe.ViewEngine.Htmx](https://github.com/bit-badger/Giraffe.Htmx/tree/main/src/ViewEngine.Htmx)
 * Rust