compare with more relevant implementations

[anarcat]

I like that there is a comparison section in the README file. However, it compares against stuff like gethttpsforfree which is really more of a help site than a real management tool. To do a fairer comparison, one would compare with acme-tiny from the same author, for example.

I would also be curious to see this compared with other implementations I have identified like simp_le. A more complete list is in the let's encrypt wiki.