Improve release guide about hipparchus

[axkr]

Dependabot already creates 3.0 changes. Is this intended?

• axkr/symja_android_library#832

[maisonobe]

No, it is not intended and indeed the dependencies reference the 3.0-SNAPSHOT version, not the upcoming final 3.0.

Edit: Scratch that, they reference 3.0. I'll have a look at it

[maisonobe]

After a quick look, I think it is due to the repositories list.

For the general public, the version is still only available in the staging repository and the latest official version in maven central is still 2.3.

For expert uses, our own repository that is triggered by the Continuous Integration framework provides all versions, even development ones. When the branch for 3.0 release was created during the release process, the maven artifacts were pushed there automatically.

So I guess you reference our repository in Symja.