docs: add ngx-digits-only (#2371)

Author: jdegand

README.md

@@ -1448,6 +1448,7 @@ Current Angular version: [![npm version](https://badge.fury.io/js/%40angular%2Fc
 * [ngx-mat-menu-hover](https://github.com/Gamekohl/ngx-mat-menu-hover) - This Angular directive provides functionality to handle hover menu behavior, allowing menus to open when hovered over and close when the mouse leaves.
 * [ngx-highlight](https://github.com/SynTronic/ngx-highlight) - Angular directives for highlighting search matches in text, built on the [CSS Custom Highlight API](https://developer.mozilla.org/en-US/docs/Web/API/CSS_Custom_Highlight_API).
 * [ngx-liquid-glass](https://github.com/anushsharma27/ngx-liquid-glass) - Angular directive for Apple-inspired liquid glass effects with DOM-backed refraction and configurable edges.
+* [ngx-digits-only](https://github.com/Sepehr-Aghdasi/ngx-digits-only/tree/master/projects/digits-only) - Angular directive for smart numeric inputs — digit filtering, formatting, and validation without pulling in a full masking library like `ngx-mask`.
 
 ### DOM