docs: Fix incorrect handling of env variable data type (#8979) — thanks, @AvilaJulio!

Author: AvilaJulio

docs/pages/guides/recipes/query-acceleration/disabling-pre-aggregations.mdx

@@ -47,7 +47,7 @@ following file structure:
 
 ```javascript filename="env.js"
 module.exports = {
-  pre_aggregations_enabled: process.env.PRE_AGGREGATIONS_ENABLED || true
+  pre_aggregations_enabled: process.env.PRE_AGGREGATIONS_ENABLED !== 'false'
 }
 ```
 
@@ -83,4 +83,4 @@ the reason why `measures` are defined as such above.
 [ref-pre-aggs]: /product/caching#pre-aggregations
 [ref-env-vars-recipe-yaml]: /guides/recipes/code-reusability/environment-variables#yaml-files
 [ref-env-vars-recipe-js]: /guides/recipes/code-reusability/environment-variables#javascript-files
-[ref-context-symbols-transpilation]: /product/data-modeling/dynamic/schema-execution-environment#context-symbols-transpile
+[ref-context-symbols-transpilation]: /product/data-modeling/dynamic/schema-execution-environment#context-symbols-transpile