docs: add ngx-schematic-builder (#1371)

Author: jdegand

README.md

@@ -572,6 +572,7 @@ become an Angular expert.
 * [angular-rspack](https://github.com/nrwl/angular-rspack) - [Rspack](https://github.com/web-infra-dev/rspack) plugin and tooling for Angular applications.
 * [ngx-devkit-builders](https://github.com/Celtian/ngx-devkit-builders) - This package contains Architect builders used to build and test Angular applications and libraries.
 * [angular-static-assets-hash](https://github.com/sitelint/angular-static-assets-hash) - Create a list of Angular static assets and a hash for each file.
+* [ngx-schematic-builder](https://github.com/kstepien3/ngx-schematic-builder) - A tool for building Angular schematic projects. Compiles and packages your custom schematics, preparing them for publishing and use.
 
 #### CLI