* elaborate on runtime API

* clarify what to do if the runtime API calls fail

* Update roadmap/implementers-guide/src/node/approval/approval-voting.md

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* Update roadmap/implementers-guide/src/node/approval/approval-voting.md

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>