remove size-saving information

Relative size-saving depends on the size of the custom app

Author: MikeMcC399

docs/BestPractices.md

@@ -216,7 +216,6 @@ without copying the npm & Yarn package managers.
 In Docker images based on Node.js >=26, Yarn is already removed.
 
 The result is a smaller and hardened final image with no package managers.
-The size savings are typically about 2% or 3%.
 
 The examples below build with npm.