chore(Mathport/Syntax): add syntax for coherence tactic (#310)

Should have been added after leanprover-community/mathlib3#13417.

Co-authored-by: Scott Morrison <[email protected]>

Author: kim-em

Mathlib/Mathport/Syntax.lean

@@ -523,6 +523,9 @@ syntax mono.side := &"left" <|> &"right" <|> &"both"
 /- E -/ syntax (name := ghostSimp) "ghost_simp" (" [" simpArg,* "]")? : tactic
 /- E -/ syntax (name := wittTruncateFunTac) "witt_truncate_fun_tac" : tactic
 
+/- M -/ @[nolint docBlame] syntax (name := pure_coherence) "pure_coherence" : tactic
+/- M -/ @[nolint docBlame] syntax (name := coherence) "coherence" : tactic
+
 namespace Conv
 
 -- https://github.com/leanprover-community/mathlib/issues/2882