v0.2.3

[ihorzenich]

Combine all PR for version 0.2.3 together, update Changelog.md with:

• Add example of shorter modifier syntax #52
• Add custom prefixes syntax (+prefix-scope) #53
• Fix not-generated tag #54

[kizu]

Merged two of the three PRs manually (and published as bemto.jade@0.2.3), so I'm closing this.