Improve Github releases apperance

[f1ames]

Are you reporting a feature request or a bug?

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Provide detailed reproduction steps (if any)

Each tag pushed to remote is also treated as GH Release (https://github.com/ckeditor/ckeditor4-angular/releases) automatically, however it doesn't include any useful information (title, changelog, any description). See ho it looks here vs. how it looks in ckeditor5-react.

I think we could improve it (by drafting releases manually first to see how it works and then go with some automation).

Also CKE5 has some script for this so we could probably utilize it somehow, see:

• https://github.com/ckeditor/ckeditor5-react/blob/master/scripts/publish.js
• https://github.com/ckeditor/ckeditor5-dev/blob/master/packages/ckeditor5-dev-env/lib/release-tools/tasks/releasesubrepositories.js
• https://github.com/ckeditor/ckeditor5-dev/blob/master/packages/ckeditor5-dev-env/lib/release-tools/utils/creategithubrelease.js