Create a prior art and alternatives section in readme

[casey]

• Make
• https://github.com/jakedeichert/mask
• MS Just
• https://github.com/egoist/maid
• https://github.com/sagiegurari/cargo-make
• https://github.com/VladimirMarkelov/haku
• https://github.com/go-task/task

[casey]

I started the section and added a couple, but should still add the rest eventually: #1008

[xonixx]

Hey @casey! You might want also to mention my creature https://github.com/xonixx/makesure

Some exclusive features of it:

1. The syntax of Makesurefile is a valid shell, so user gets highlighting for free.
2. The tool doesn't need traditional installation, since it's single-file POSIX shell script (in fact 99% AWK) that you put in project repo.
3. The recipe may include very simple but very powerful @reached_if modifier. It allows to skip execution (together with sub-dependencies) if already satisfied (idempotence). I wonder if just needs this feature and/or could incorporate.

Other than that, conceptually and feature-wise it's close to just except for syntax and this.

[casey]

Nice, that looks really cool. I especially like that it's just shell and zero install. Adding it here.

[xonixx]

Thank you!