🏷️ Update tagName to optionally be an array

The `Registry` [already allows][1] the `tagName` property to be an
array.

This change updates the types to reflect that.

[1]: 634e50f4d7/src/registry.ts (L127)

README.md

@@ -18,7 +18,7 @@ At the very minimum a Blot must be named with a static `blotName` and associated
 class Blot {
   static blotName: string;
   static className: string;
-  static tagName: string;
+  static tagName: string | string[];
   static scope: Scope;
 
   domNode: Node;

src/blot/abstract/blot.ts

@@ -6,7 +6,7 @@ import Scope from '../../scope';
 export interface BlotConstructor {
   blotName: string;
   className?: string;
-  tagName: string;
+  tagName: string | string[];
   new (scroll: Root, node: Node, value?: any): Blot;
   create(value?: any): Node;
 }
@@ -25,7 +25,7 @@ export interface Blot extends LinkedNode {
     defaultChild?: BlotConstructor;
     requiredContainer?: BlotConstructor;
     scope: Scope;
-    tagName: string;
+    tagName: string | string[];
   };
 
   attach(): void;

src/blot/abstract/container.ts

@@ -5,7 +5,7 @@ import ParentBlot from './parent';
 class ContainerBlot extends ParentBlot {
   public static blotName = 'container';
   public static scope = Scope.BLOCK_BLOT;
-  public static tagName: string;
+  public static tagName: string | string[];
 
   public prev!: BlockBlot | ContainerBlot | null;
   public next!: BlockBlot | ContainerBlot | null;

src/blot/abstract/shadow.ts

@@ -8,7 +8,7 @@ class ShadowBlot implements Blot {
   public static className: string;
   public static requiredContainer: BlotConstructor;
   public static scope: Scope;
-  public static tagName: string;
+  public static tagName: string | string[];
 
   public static create(value: any): Node {
     if (this.tagName == null) {