Describe KAGRA/Subgroups/VIS/TypeB/PostO3 here.

Sources of information:

 * E-mail thread: [kagra-seis 03117] List of VIS improvement items after O3.
 * [[http://gwwiki.icrr.u-tokyo.ac.jp/JGWwiki/KAGRA/Subgroups/VIS/BrainStorm/ToDo2019|VIS Brainstorm page]].
 * [[https://onedrive.live.com/view.aspx?resid=8E8081C20FE5EC3A!2278&ithint=file,xlsx&authkey=!AMFNtNa-Y6CVp94|Post-O3 task list]] from [[http://gwwiki.icrr.u-tokyo.ac.jp/JGWwiki/KAGRA/Subgroups/VIS/VISMinutes20191101|Agenda/Minutes 2019/11/01]]