docs: Introduce pg_search in its own sentence

Author: jamessewell

README.md

@@ -36,7 +36,7 @@
 
 ## ParadeDB for Rails
 
-The official ActiveRecord integration for [ParadeDB / pg_search](https://paradedb.com), including first-class support for managing BM25 indexes and running queries using the full ParadeDB API. Follow the [getting started guide](https://docs.paradedb.com/documentation/getting-started/environment#rails) to begin.
+The official ActiveRecord integration for [ParadeDB](https://paradedb.com), including first-class support for managing BM25 indexes and running queries using the full ParadeDB API. ParadeDB is powered by [`pg_search`](https://github.com/paradedb/paradedb), a Postgres extension that adds Elastic-quality full-text search, vector retrieval, and aggregations. Follow the [getting started guide](https://docs.paradedb.com/documentation/getting-started/environment#rails) to begin.
 
 ## Requirements & Compatibility