Release page: Don't call the .tar.gz 'precompiled'

[davidmehren]

Our release bundle contains the frontend bundle since 1.7.
Calling that "precompiled" is technically wrong and confusing.
Compilation means that architecture-specific object code is generated, which is not the case for our frontend bundle. Users might think that our release bundle is in some way architecture-specific, if we refer to compilation.

We should omit the word "precompiled" from the release page. Instead we could use "Ready to use archive" as the heading and "Includes pre-build frontend bundle" as a note below that.