update signal sentence

Author: LadyBluenotes

src/routes/reference/basic-reactivity/create-signal.mdx

@@ -16,7 +16,7 @@ description: >-
 ---
 
 Creates a reactive state primitive consisting of a getter (accessor) and a setter function that forms the foundation of Solid's reactivity system.
-Signals are optimized for frequent reads and infrequent writes
+Signals use a pull-based reactivity model where tracking subscriptions (reads) is lightweight, while updates (writes) trigger dependency tracking and effect re-execution, making them optimized for frequent reads and infrequent writes.
 
 ## Import