Add changes to the release pages instead of always the same flashing tutorial

[serialrf433]

I think it would make sense to have the specific changes listed in the release page.
For example i asked myself what is new in the 0.4.0 version released 15 minutes ago but can not read any description in here: https://github.com/thatSFguy/reticulum-rnode/releases/tag/v0.4.0

I expect it should be simple to use the LLM to summarize in human readable text the changes to not have to add just a link to the git changelog like currently done on the Android application.

The current 'Flashing' and 'Manual Flashing' from the release page would make sense to be moved in here: https://github.com/thatSFguy/reticulum-rnode/blob/master/README.md

In the release page you can link to the flashing howto like for example such a link: https://github.com/thatSFguy/reticulum-rnode#flashing (not currently a working link, because of missing flashing section)