[About Module] Review css used in web views in module

[ludovic35]

use same as android https://github.com/Orange-OpenSource/ods-android/tree/19-ods-module-about/module-about/src/main/res/raw https://github.com/Orange-OpenSource/ods-android/blob/19-ods-module-about/module-about/src/main/java/com/orange/ods/module/about/OdsAboutFileScreen.kt