Mention requirement to set alpha channel in changelog for 0.9

[LukasKalbertodt]

Hi there! Really awesome library, thanks for maintaining it!

I just updated a project of mine from 0.3 to 0.9 by doing each intermediate updated individually. Everything just worked till 0.8, but updating from 0.8 to 0.9 suddenly resulted in a completely black screen. I finally found out that the issue was that I never wrote to the alpha channel. But for the previous pixel versions that was fine. But with 0.9 I had to manually write 255 to the alpha channel of each pixel at least once.

I could imagine that I was always supposed to write the alpha channel. But since it has become required since 0.9, maybe consider mentioning this in the changelog. Could save some others some time.

[parasyte]

👋 Thanks for the report and kind words.

There is a line in the changelog for the feature:

Make the background/border color configurable, and support basic alpha blending (#236)

You're right that it should also mention the breaking change with the new default BlendState from that change which enabled alpha blending. I'll just go ahead and make that update now.

[LukasKalbertodt]

Thanks a lot for the quick fix :) Looks good to me!