Add missing pids argument to documentation of editing a record draft

[apirogov]

Currently, in the docs there is no mention that on this request the possibly existing pids from the record also must be sent.

Omitting this yields no problems for new record drafts, as there are no pids registered yet. But editing the metadata of published drafts runs into problems such that not adding pids effectively "breaks" the publishing of changes until a new version is created.

By documenting this requirement the issues can be avoided, but ideally, an incomplete request should not be able to "break" anything, in my opinion.