Add lego

ACME client library and CLI tool

README.md

@@ -661,6 +661,7 @@ See [go-hardware](https://github.com/rakyll/go-hardware) for a comprehensive lis
 
 * [BadActor](https://github.com/jaredfolkins/badactor) - An in-memory, application-driven jailer built in the spirit of fail2ban
 * [go-yara](https://github.com/hillu/go-yara) - Go Bindings for [YARA](https://github.com/plusvic/yara), the "pattern matching swiss knife for malware researchers (and everyone else)"
+* [lego](https://github.com/xenolf/lego) - Pure Go ACME client library and CLI tool (for use with Let's Encrypt)
 * [passlib](https://github.com/hlandau/passlib) - Futureproof password hashing library.
 
 ## Serialization