docs: fix ib-to-eb link

Author: will-break-it

docs/workshop/eb-reference.d2

@@ -123,24 +123,24 @@ EB0 -> volatile.RB: "Ledger Ref" {
 
 # IB references
 
-IB4 -> EB1: {
-  class: to_eb_arrow
+IB4 -> EB1: "Ledger Ref" {
+  class: ledger_link
 }
 
-IB3 -> EB1: {
-  class: to_eb_arrow
+IB3 -> EB1: "Ledger Ref" {
+  class: ledger_link
 }
 
-IB2 -> EB: {
-  class: to_eb_arrow
+IB2 -> EB: "Ledger Ref" {
+  class: ledger_link
 }
 
-IB1 -> EB: {
-  class: to_eb_arrow
+IB1 -> EB: "Ledger Ref" {
+  class: ledger_link
 }
 
-IB -> EB0: {
-  class: to_eb_arrow
+IB -> EB0: "Ledger Ref" {
+  class: ledger_link
 }
 
 direction: left