Documentation of Update button needs more info

**Describe the enhancement**

In the documentation of the Update button, add information about what CAPI information is requested, and to what endpoints that information is sent. In particular, is it sent to plugins also?

**Additional context**

The question arose from a question on Reddit, where a user asked how he could ensure that an Exobio discovery was reported to the Canonn database. The question then became if the update info will be resent to the EDMC Canonn plugin, or if it only sent to the EDDN/EDSM/Inara endpoints (assuming they're enabled).

As the current documentation doesn't seem to say what EDMC does on Update, I suggest the clarification should be added.

No documentation file or test is named. Locate the documentation for the Update button, then trace the current CAPI handling to identify the requested information, its destinations, and whether plugins receive it. Done means the documentation clearly answers these questions, including the EDDN, EDSM, Inara, and Canonn-related behavior described in the issue.

Written by the indexing model from the issue text.