doc(readme): add deprecation notice

[GitToTheHub]

Platforms affected

Android, iOS

Motivation and Context

• This plugin is deprecated since cordova-ios 8.0.0 and cordova-android 15.0.0. Functionality has moved to the platform cores. Also a Status Bar JavaScript API was introduced on these platforms to handle the status bar additionally.
• Add links to the blog articles which mention the deprecation and the suggested changes.

Some things to note about the cores:

1. cordova-android lagged the possibility to hide the status bar completely, which is fixed by PR #2000 (fix(statusbar): hide status bar correctly cordova-android#2000) but not released yet.
2. Since cordova-android 15.1.0 the dark/light appearance of the status bar can bet by the Status Bar JS API (fix(SystemBarPlugin): remove canEdgeToEdge check for execute method cordova-android#1971). On iOS this is done automatically since iOS 18.5. For iOS older than 18.5 the PR #1689 (feat(statusbar): change dark/light appearance according to background color cordova-ios#1689) fixed that, but which is not released.
3. cordova-android lags the possibilty of using the config.xml preference<preference name="StatusBarOverlaysWebView" value="true" /> in non-edge-to-edge mode, because StatusBarOverlaysWebView is not supported by the cores. PR #1991 on cordova-android (fix(statusbar): restore StatusBarOverlaysWebView support in non-edge-to-edge mode cordova-android#1991) adds the functionality back to Android, but @dpogue mentioned, that this should be done by <meta name="viewport" content="viewport-fit=cover|contain"> by a MutationObserver in JavaScript. On iOS this behaviour can already be obtained by using <meta name="viewport" content="viewport-fit=cover“>. @dpogue opened a PR #2010 on cordova-android (WIP on theme-color/viewport-fit cordova-android#2010) which would resolve this.

Description

Testing

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[GitToTheHub]

If no one has any objections I would merge this.

[jcesarmobile]

has been a vote for deprecating the plugin?
I can't find any discussion about it.

As far as I know, the platform implementations are not total replacement of the plugins and I've seen community members recommending using the statusbar plugin for the cases not covered by the platform implementations.

[GitToTheHub]

For me it looked like it is deprecated as also no more work is done one this plugin. Hiding the status is now fully functional on Android and iOS. Setting the dark/light appearance is also possible. Which functionality offers this plugin, which the core functionality does not offer?

[jcesarmobile]

There are more plugins where no work or little work is done, that doesn't mean they are officially deprecated, for deprecating a plugin a vote thread is needed with 3 positive votes.

Or at least that's how we have deprecated plugins in the past.

I'm not sayin we shouldn't deprecate it, I'm saying we need to vote first.

[GitToTheHub]

Ok didn't know. Than I will start a vote thread.