Update .env.example to include base image configuration options for Docker, enhancing clarity for users setting up the environment.

Author: jaydrogers

.env.example

@@ -9,13 +9,9 @@ BOOST_NPM_EXECUTABLE_PATH="./vendor/bin/spin run node npm"
 
 OCTANE_SERVER=frankenphp
 
-# The serversideup/php image variation being benchmarked (set by the
-# PHP_VARIATION Docker build arg), e.g. fpm-nginx or frankenphp.
-#PHP_VARIATION=
-
-# Where benchmark stages write their raw result files.
-#BENCHMARK_RESULTS_PATH=
-
-# URL the web server load test targets. Only needed when the app cannot
-# reach itself over HTTP (the self-test tries localhost, then APP_URL).
-#BENCHMARK_HTTP_URL=
+############################################
+# Base Image Configuration (choose an image from https://hub.docker.com/r/serversideup/php)
+############################################
+# BASE_OS=trixie
+# PHP_VERSION=8.5
+# PHP_VARIATION=fpm-nginx