Update README.md

[6480k]

Fixed some incorrect information and added useful info, specifically for crops and crop objects.

Some notes: I removed the note about flowers not growing on trellises and having colors because I believe the actual issue is that flowers cannot regrow and have colors (due to the placement of the regrowth sprite and color sprites in vanilla). Most people make trellis crops regrow, which is probably how the original issue was discovered.

[Pathoschild]

Thanks for the pull request! This is merged into the new spacechase0/StardewValleyMods repo.