[Handbook] Remove TrueOS recommendation

[carlavilla]

Summary

Based on this two links [1][2] I think we can stop recommending TrueOS in our Handbook.

I prefer to contrast it with you before committing

[1] https://www.phoronix.com/scan.php?page=news_item&px=No-More-TrueOS
[2] https://www.ixsystems.com/community/threads/is-trueos-abandoned.82183/#post-574390

Test Plan

Compile the handbook.

[bcr]

Looks good to me and I think at this point, it makes more sense to recommend other desktop-oriented BSDs.