Remove syntax diagrams

Author: antonmedv

spec/v0.1.md

@@ -338,7 +338,4 @@ ABNF Grammar
 A formal description of MAML's syntax in ABNF format
 ([RFC 5234](https://www.ietf.org/rfc/rfc5234.txt)).
 
-A visual representation of the MAML syntax is available in the
-[syntax diagram](/spec/v0.1/diagram.md).
-
 <<< @/spec/v0.1/maml.abnf