docs: add community extensions website link to README and extensions docs (#2014)

Author: ismaelJimenez

README.md

@@ -160,6 +160,8 @@ Want to see Spec Kit in action? Watch our [video overview](https://www.youtube.c
 
 ## 🧩 Community Extensions
 
+🔍 **Browse and search community extensions on the [Community Extensions website](https://speckit-community.github.io/extensions/).**
+
 The following community-contributed extensions are available in [`catalog.community.json`](extensions/catalog.community.json):
 
 **Categories:**

extensions/README.md

@@ -68,6 +68,8 @@ specify extension add <extension-name> --from https://github.com/org/spec-kit-ex
 
 ## Available Community Extensions
 
+🔍 **Browse and search community extensions on the [Community Extensions website](https://speckit-community.github.io/extensions/).**
+
 See the [Community Extensions](../README.md#-community-extensions) section in the main README for the full list of available community-contributed extensions.
 
 For the raw catalog data, see [`catalog.community.json`](catalog.community.json).