Add Changelog to the manual

[ivan-mogilko]

Strangely this was never done, but I think we should add a copy of the full change log to the manual. Not sure if anyone reads changes.txt that comes along with the editor, but it will be more visible in the manual IMO.

[ericoporto]

I guess process wise this means a manual has to be released right before the Editor is released. This is because there is a small timing issue that the Changes.txt for the specific version that is released usually get it's final touches right before tag creation.

The CI here runs much faster than the CI on the main repository, so it could still "win the race", if both are updated simultaneously. I am assuming this is done manually, duplicating the information in both places.

I don't have any current idea for doing it automatically.

Whatever is the process that comes up, once we think it works, it could be documented in https://github.com/adventuregamestudio/ags/wiki/Public-release%3A-procedure#changelog

Other alternatives would be offering to open Changes.txt at the end of installation or having a link to view it somehow from the Editor “Help” menu component.