Update "App Actions on Windows for web apps" docs — edge-app-actions-on-windows-for-web-apps flag no longer required #3980

Link to the documentation page:

https://learn.microsoft.com/microsoft-edge/progressive-web-apps/how-to/app-actions

Description of the issue:

The documentation instructs developers to enable the edge-app-actions-on-windows-for-web-apps flag (via edge://flags) to use App Actions on Windows for PWAs. As of Microsoft Edge 137, App Actions is a standard feature and this flag is no longer required (and the Actions flag no longer appears in edge://flags in current builds).

This has generated user confusion — developers/testers follow the docs, search for the flag in edge://flags, don't find it, and file it as a bug (the feature is actually working as designed).