Add docs explain new flag css trigger static content

src/guides/v2.3/frontend-dev-guide/css-topics/css_flag_deploy_enabled.md

@@ -0,0 +1,45 @@
+---
+group: frontend-developer-guide
+title: Trigger flag deploy styles for only enabled modules
+functional_areas:
+  - Frontend
+---
+
+## What is in this topic {#practice_over}
+
+This topic features a step-by-step illustration of how to change a flag trigger magento process css styles.
+
+## Changing flag trigger deploy static contents
+
+1. Add inside to app/etc/env.php or app/etc/config.php. Add following line to the top array
+
+```php
+return [
+'static_content_only_enabled_modules' => true,
+//...other lines
+]
+```
+
+This meaning magento only deploy static content styles from enabled module to final css files (styles-l.css, styles-m.css). If set value to false magento will always deploy all styles no matter modules enabled or disabled!
+
+
+2. After modify php file. Make sure re-run setup upgrade for update config flag 
+
+
+```bash
+php bin/magento setup:upgrade
+```
+
+or
+
+```bash
+php bin/magento app:config:import
+```
+
+Now re-run deploy static content as normally if need
+
+```bash
+php bin/magento setup:static-content:deploy en_US
+```
+
+Ensure you replace en_US with the appropriate locale code if your store uses a different language

src/guides/v2.4/frontend-dev-guide/css-topics/css_flag_deploy_enabled.md

@@ -0,0 +1,45 @@
+---
+group: frontend-developer-guide
+title: Trigger flag deploy styles for only enabled modules
+functional_areas:
+  - Frontend
+---
+
+## What is in this topic {#practice_over}
+
+This topic features a step-by-step illustration of how to change a flag trigger magento process css styles.
+
+## Changing flag trigger deploy static contents
+
+1. Add inside to app/etc/env.php or app/etc/config.php. Add following line to the top array
+
+```php
+return [
+'static_content_only_enabled_modules' => true,
+//...other lines
+]
+```
+
+This meaning magento only deploy static content styles from enabled module to final css files (styles-l.css, styles-m.css). If set value to false magento will always deploy all styles no matter modules enabled or disabled!
+
+
+2. After modify php file. Make sure re-run setup upgrade for update config flag 
+
+
+```bash
+php bin/magento setup:upgrade
+```
+
+or
+
+```bash
+php bin/magento app:config:import
+```
+
+Now re-run deploy static content as normally if need
+
+```bash
+php bin/magento setup:static-content:deploy en_US
+```
+
+Ensure you replace en_US with the appropriate locale code if your store uses a different language