Update Ibexa Cloud during 3.3. update or 4.x migration (#2518)

* update_from_3.3.md: platformsh_prestart_cacheclear.sh changed.
* to_4.0.md: opportunity to review Ibexa Cloud changes.

(cherry picked from commit 65b2d91)

Author: adriendupuis

docs/update_and_migration/from_3.3/to_4.0.md

@@ -200,3 +200,16 @@ Finally, generate the new GraphQl schema:
 ``` bash
 php bin/console ibexa:graphql:generate-schema
 ```
+
+### Ibexa Cloud
+
+Update Platform.sh configuration and scripts.
+
+Generate new configuration with the following command:
+
+```bash
+composer ibexa:setup --platformsh
+```
+
+Review the changes applied to `.platform.app.yaml`, `.platform/` and `bin/platformsh_prestart_cacheclear.sh`,
+merge with your custom settings if needed, and commit them to Git.

docs/update_and_migration/from_3.3/update_from_3.3.md

@@ -315,6 +315,20 @@ Run the following scripts:
     composer update "symfony/*"
     ```
 
+#### Ibexa Cloud
+
+Update Platform.sh configuration and scripts.
+
+Generate new configuration with the following command:
+
+```bash
+composer ibexa:setup --platformsh
+```
+
+Review the changes applied to `.platform.app.yaml`, `.platform/` and `bin/platformsh_prestart_cacheclear.sh`,
+merge with your custom settings if needed, and commit them to Git.
+
+
 ### v3.3.14
 
 #### VCL configuration